Hi. Apologies for a long post in advance.
I have a very frustrating problem that I believe is common amongst my gen of lancer, but for the life of me I cannot figure out what is wrong.
I bought my 09 GTS with 70k miles. It ran pretty well overall and still does except for one seriously annoying issue. Around 100k miles, maybe a little less than, the car started rough idling at stops, so much so that it struggles to keep itself on. It regularly dies and I have to restart it in the middle of traffic, or in a more dangerous situation mid turn when I push in the clutch. Basically it will rapidly lose rpms when you push the clutch in and then sometimes will just straight up shut off, or most of the time it will bounce between less than 100 rpms and 500 and then shut itself off.
This has been going on for over 2 years. I've been too broke most of the time to try and get it into shops. However on 2 occasions I have taken it into local places, to not have the problem fixed. Both places did the same thing. Cleaned out the throttle body and the MAF. The first time they did this it helped, and somewhat had the opposite issue afterwards. I'd come to stops and be revving at like 2k rpms with no foot on the gas. Over time the problem resurfaced tho and went back to the way it came in. The second time I took it in was last week, at a different place, they did the same thing pretty much, as well as new spark plugs, and it ran very well and idled perfectly for about 40 miles. Then went right back to doing it again. I also replaced the custom air filter it has a few days ago, which was their recommendation when I called to tell them it's still not idling properly. Still stalling. Also i should note that it doesnt 100 percent of the time do this. It seems like it mainly does it after the car has been warmed up and the outside temperature is about 65 degrees, running best when its cold outside. Sometimes you get a good stop and a perfect idle. If anyone has any similar problem and a solution please share this with me, as I am very much so attached to this car, but it is giving me serious stress just based on the fact that nobody seems to be able to pinpoint what is wrong. I will be the first to admit I am not mechanically skilled. I just need some suggestions for when I take it back in shortly to the shop it just came from.
If the following info helps, it is an 09 GTS, 145k miles, manual, it does have an aftermarket exhaust and aftermarket air intake tube and filter. It has an aftermarket stero which was wired poorly, but has been checked out and ok'd after I fixed a short it had ( I bring this up because I have heard wiring may cause this issue), I had the battery checked and it came back totally fine. As stated above other than this one problem, it runs very well I'd say. Just coming to stops is a nightmare and sketches me out, and I really don't want to drive heel toe everywhere I go just to keep the car on. Lol. Any suggestions would be greatly appreciated. Thanks for reading and sorry for the long post.