Persistent problem I cant get fixed
I have a 2020 Ford Fusion 1.5L ecoboost i bought a little over a year and a half ago with about 85k miles on it. It ran great until the last 4 months or so. Its had an issue where it has erratic RPM fluctuations when driving at cruising speed. It will start relatively mild but once it starts, it continues to get worse over a few days until eventually it gets so bad it goes into limp mode and throws the check engine light. I have had it in 3 times now.
First time they said the MAF sensor was dirty so they cleaned it and it drove great for a month.
Second time it started doing it again I took it to the same mechanic. This time it had a code for the MAP sensor. It had a bad O ring and leaked oil into the cam sensor. They replaced the MAP sensor and cleaned the cam sensor. Again it drove great for a month.
The third and most recent time it had a check engine light on and I got the code read at Autozone. It had a bad purge valve but was driving fine. I drove it like that for a week until the rpm issue started up again. I replaced the purge valve assembly myself but that didnt fix it so I took it back in to the mechanic AGAIN. This time they said the only codes they were getting were misfire codes. They said they werent sure what the exact cause is since it was only misfire codes and nothing else. So they did a pressure test to make sure it wasnt a coolant intrusion and said it may just be spark plugs and ignition coils. They replaced those and it drove ok for a day. Now its back to doing the same things its been doing.
So im at a loss and losing my mind. Has anybody else had a similar issue? A buddy said it could maybe be the throttle position sensor. Or maybe a partially clogged fuel injector. Without it throwing codes as soon as it starts I dont know how to determine what it is, especially after addressing all the things I already have had fixed. Any help would be appreciated.