ryder2101

Like the title states I'm stumped trying to figure this out. One day I boosted one time to bout 12psi and went to band practice. Later that night I got in my car, fired it up "note it is wibter" revs went to 2k like normal and slowly was dropping 1800,1600,1500, wideband leans out car dies. So I fired it up again, same thing, I have to keep the revs up to keep it running and at same time car will have a hesitation "miss" if you rev in neutral or hold at any rpm. So I left to go home and also noticed while missing and idleing weird vacumm will bounce around anywhere from 8 psi"at the roughest idle/hesitation to 10,15,18 back and forth, seems to bounce around when its running like crap. So I'm cruising at different speeds and gears watching wideband. And while I'm barely touching throttle its 17.8 to 18.0 and flat lines the wideband gauge in lean, where before this happened car would be in the 12-13 area. I noticed one time when tank was almost empty the air fuel corrected to where it ran previously. But that was only once. And when I filled up, it has never done that again. I'm stuck I've checked voltages on tps. Getting .4 shut 4.7 open, change coolant temp sensor, added fuel pump relay. Messed with iacv. Checked timing 15', fixed a exhaust leak. All new Coilpacks, checked plugs they seemed fine. When you go wot the air fuel is still alittle higher than before. But gets a ton better. It's only when on light throttle does it lean out badly and makes car feel like its dragging a piano, and you can feel it jerking with a lean out. And when warm it gets a little better with starting it. Cold starts are really bad it will drop to 300/400 Rpm and bucking then it sometimes will come up or shut off. And vaccum will be way off while its leaning and bucking. Idk why it would do this all the sudden. It was fine , then poof it runs like crap. Plz help. Here's list of whats done to it. Note that car ran good before this happened, but always had slight studder when reved in neutral.


Sr20det blacktop s13
Gt2876r
Fmic
Sard 850cc
Enthalpy ecu
Fpr
Walbro 255
Manual boost controller
Wideband
Boost gauge
Metal head gasket
Megan tubular mani
Aftermarket turbo elbow
3in straight exhaust to Apexi can

I've checked tps .4 to 4.7 "new tps not installed"
Coolant temp sensor
New Coilpacks
Fixed exhaust leak
New walbro 255 "not installed"
Messed with iacv "new iacv. Not installed"
New Ignitor
New pcv valve
Check maf seemed to be working
Check compression
139,141,142,141. While warm, wot, fuel pump fuse pulled

I'm stumped, any help would be awesome, like i said car since I bought it always has a weird stumble at idle, but never did while driving or boosting. I never found out why it did, it was barely noticeable before. Now cold start lean out stumble and leanout cruising at like .5% throttle. If you need any more info just tell me. I really want to no what is going on and how to fix it the right way, like it ran before and fix the stumble/miss at idle, when I purchased it. Thanks a lot fellas, I.searched but couldn't find anything like the situation I'm having