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crappy idle, stuttering while crusing

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Pesky idle problem


I have a 1991 subaru legacy ej22 a/t fwd and it has developed an issue. It started with the cel coming on when the weather got cold i assumed the cheap chinese o2 sensor couldnt keep up temperature wise and it tripped a code. I ignored it. Then the cranking issues.


On cold morning 41 degrees F (im in georgia, thats cold) the car would crank up fine but if i stopped, say at a store and got back to the car while the engine was warm it didnt want to crank. Id feather the gas and itd roar to life after a few cranky seconds. I also developed an idle issue. The idle kept dropping to 3-200 rpm then bounce back to 500 slowly. If i was turning sharp and the rpms dropped i got a nice stalled engine. It would crank right back up and id be on my way. I diagnosed it as ecu coolant temp sensor. Replaced it, bye bye cel. Then the stuttering. My wife and mother drove the car while i was at work. After i started driving i noticed unless you gave it 3/4 throttle from a stop, it barely moved. It was if it was being held back. If you went WOT it'd jump off the line full of life but not if you eased into it.


But wait theres more! While you were crusing the car would jerk horribly as if it was starving for fuel or flooded, it bucked, shaked and would only go away if you where increasing speed or would go away for maybe a minute if you go WOT then let off. I thought fuel pump, went to the autoparts store that had a different wiring setup and there was 2/3 the size of my pump but claimed the pump went to my car. I took a paid day off (my only one) to go to the salvage yard, found a 96 fuel pump, swapped the pump from the 96 housing to the 91 so the sender would work, driving on the highway and here comes the shutter about 15 mins into cruising, well ****. I replaced the vaccum line to the fuel regulator because it was collapsed. No difference, irratic low idle, sluggish acceleration and shuttering engine persisted, no cel.


I disconnect the o2 sensor, no more shutter, but now cel and the idle is weak still and now is rougher. I go to the local part store and spray the maf sensor, plugged the 02 back in, no more code and drove home. I didnt notice a shutter but it was a shortish trip and the rpms still drop way to low. The plugs and wires are new (6k miles) and i cant figure out while it idles so low. Plan to clean the iacv when im not inbetween houses and have a physical address to get the gasket mailed too. The engine has always had a mild miss, not enough to trip a code but noticible puff at idle. I tested using smoke in vaccum booster for vaccum leaks, i saw nothing. Any suggestions?

Edit, o2 connected and maf cleaned, was crusing, still a low crap idle, and the sputtering is back. Im lost.

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