drolds1

When posting a question like this, it helps if you supply some details about your car.  For instance, which engine do you have?  This is an Internet guess but, due to defective engine blocks, Ford's I-4 EB engines have been known to develop coolant intrusion into cylinders 2&3, which gets burnt. There would be no obvious leaks in such a case, but a professional diagnosis is in order here.
 
https://youtu.be/_8nQ1NZW_GI?feature=shared

If the battery is original then 4yrs is a bit of a gift in today's world for a battery.

Thanks for the update.  I meant to mention the updated driveshaft in my previous post but forgot.  At least it wasn't the PTU or rear diff. 
 
Just for reference, $1800 CAD converts to $1335 USD as of today.  At your mileage, I'd still consider changing the PTU fluid if it's never been done.

Does this remote start brand advertise that it can interface with the factory climate control?  If not, then you'll have to leave your HVAC system on when you shut the car off.  The best source of information in your case would be the manufacturer's tech support line instead of asking us here, as it's unlikely you'll find a member who's familiar with your particular system.

Adding to this, have you ever changed the fluid in the PTU and/or rear differential?
 
On thing confusing me: you state that is present on acceleration but occurs either in D or N.  How can you accelerate in Neutral?

An EVAP code is unrelated to this issue.
 
The Torque app doesn't have the capability to read HVAC codes.

An EVAP code is unrelated to this issue.
 
The Torque app doesn't have the capability to read HVAC codes.

I would not start fixing anything until you pull that fender, hood and bumper cover off.  You need to look for hidden damage.  Although a deer usually is not a big enough animal to total a car, it all depends on how hard it hit. 

Hi Reggieros. As drolds1 mentioned, you are dragging up old threads. And now you are quoting and thanking yourself.
 
 

Temporarily plumb in a mechanical gauge and see what the actual oil pressure is.  If you're lucky it's just the sensor, but you won't know the state of the motor without testing first.

They've had their share of recalls due to engine failures.  Again, these are considered safety issues, which the coolant intrusion in Fords is not.

https://www.justanswer.com/ford/6tesn-ford-fusion-sel-hello-2007-ford-fusion-3-0l-awd-automatic.html

The mods have no capacity to stop it. The site runner has to do something. All we can do is flag the spammers, which hides the spam and blocks the source. .  But as fast as we do that, they morph and flood us with more.   You haven't even seen how much we've gotten, as I usually hide it in the wee hours when I'm the only one awake.
 
We had the same problem on the MKZ Forum.  It's been fixed, but not by the Moderators.

I'm glad to hear that.  As I noted earlier, the 2.5 is a pretty durable engine.  There are any number of reasons for a bad compression reading in one cylinder.  As you've illustrated, not all are catastrophic failures, and you did the right thing by asking them to show you exactly what the problem was.?

I'm glad to hear that.  As I noted earlier, the 2.5 is a pretty durable engine.  There are any number of reasons for a bad compression reading in one cylinder.  As you've illustrated, not all are catastrophic failures, and you did the right thing by asking them to show you exactly what the problem was.?

A 20i4 Fusion S should have the 2.5L engine.  These are workhorses and are pretty durable engines. We haven't seen many "catastrophic" failures here with that engine, as seen more frequently with the EB engines.  Could you confirm that it's the 2.5 and how many miles are on it?
 
I agree WRT to exploring other options if it does indeed need a new engine, so long as the rest of the car is in good condition.

A 20i4 Fusion S should have the 2.5L engine.  These are workhorses and are pretty durable engines. We haven't seen many "catastrophic" failures here with that engine, as seen more frequently with the EB engines.  Could you confirm that it's the 2.5 and how many miles are on it?
 
I agree WRT to exploring other options if it does indeed need a new engine, so long as the rest of the car is in good condition.

Based on what we've learned over the years, it's a fair assumption in your case.  Still, a visual inspection is necessary to confirm.  The intake manifold needs to be removed in order to see the valves.  This also enables access for cleaning.  For years, Ford did not approve any method for removing carbon deposits on the intake valves.  Spaying solvents into the intake of a running EB engine could cause chunks of carbon to be drawn into the engine and damaging the turbocharger(s).  See this video for a demo of manual cleaning.  Ford Tech Makuloco is the guru of all things Ford around here and elsewhere on the web.  Here's an updated video demonstrating 2 newer, approved mechanical methods.

You need to get it scanned for codes, that will help a lot.

Could also be the dreaded coolant intrusion defect.  If so, hopefully you have a warranty of some kind.

From what I've read, you were lucky to get it at any price.

I don't see how you can avoid paying someone to diagnose this.  There are so many things that need to be looked at as well.
 
Without knowing which engine you have also makes it hard to even guess.   

See this thread.

Falling off a cliff presupposes starting out at the top of the cliff.

WRT to "cracking open" the OM, how true.  In my Lincoln LS forum, we had an emoji for this when we got questions that were easily looked up: "RTFM."  Allen will attest. I think you can probably figure out what those initials stand for.?
 
WRT the subject at hand, I said in my original post that I thought it could be the fob battery, but OTHO, presumably, no low key battery alert popped up.  OM: