Ok boys and girls..here goes. '88 62 with 250k. Has run great for the last 4 years I've had it. Started having some slight hesitation after startup last year but would quickly smooth out. Most recently though it got really bad after having the radiator replaced, front axle rebuild with brakes done with new master cylinder, new cap and rotor, new plug wires and plugs and new side cover gasket. Here is what's happening and what I've done to try and remedy. First off, it is not giving any codes.....It starts up after a few cranks and gets fuel ok. It idles rough and coughs, sputters when giving it throttle. After either going down the road or working at it until it warms up it eventually smooths out and runs ok, not great as far as power goes but ok. This happens any time after its been off and sitting for even a few minuts. I have an in cab vacuum gauge and after it has smoothed out it idles right at 15. When accelerating in 1st gear vacuum drops to zero and that's not mashing the pedal, that just being gentle. At higher rpm when cruising, but no throttle it sits at 20. I can hold the rpms at standstill at 2500rpm for 15 seconds and the needle sits at 20 then jumps to 25 after pedal release and back to 15. This would indicate that it's not a clogged exhaust by most standards. After reading other posts, I was convinced that it was either the fuel pressure regulator or collapsed sock at the fuel pump. Replaced both as well as fuel filter. Tested MAF, water temp sensor, ISC per FSM and all check out ok. Removed throttle body and cleaned. Bench tested and adjusted TPS per FSM. Cleaned and tested cold start injector. EFI relay works. Tried swapping in a new ECU per FSM after testing all connections and everything checked out. One possibility was maybe somehow the neutral safety switch could be affected since putting new shifter bushings in at same time of radiator replacement etc. I have heard that the ISC can test ok on the ohms, but still not be functioning. Next step is to pull it and test that it is actually functioning. After that will be injectors...If anyone has any other suggestions I would love to hear it. Thanks all!
