Ok I've had my 91 SER for a few weeks now, last week it started running on 3 cylinders, Ended up being an injector gone bad, While trying to figure that out the car got new plugs, wires, dist cap and rotor. Before and after this situation the car has a stumble at idle, Its shakes a little at idle and the rpms move a notch or 2. Thinking possible injector issues still but does anyone else have any suggestions

Now its developed into hard starting and loading up for the first few secs its running, stumbling horribly and smells of fuel, And If I rev it it does it again, after a few mins its fine, Still slit stumble at idle even at temp, Picked up a 300zx fuel filter today, cause it needs one any way.

Well the bad stumble and loading problem is fixed now, bad oring on the injector I had already replaced, Still stumbling at idle like before

have you verified spark on all cylinders? hold the end of your plug wire to the valve cover and be sure that it sparks every time that the motor turns. pop pop pop...not pop....pop pop ...pop. If that makes sense. Intermittent spark can be several other problems.

Spark seems right on, new cap, rotor, plugs and wires

You sure you didn't damage a plug when you installed? I would pull them and recheck the gap also, and see if you maybe fuel fouled them when your o-ring was leaking. Heck buy a new set for $9 and try them.

I'd check for vacuum leaks by looking for any loose or questionable hoses. Also try to pressurize the IM by either disconnecting the PCV hose from VC and blowing or hook up an air compressor and listening/feeling for air leaks.

Check the MAF voltage via consult or multimeter to make sure it isn't doing anything wierd and within spec (1.3 to 1.8V at idle and warmed up). Many people suggest regrounding the MAF to the intake manifold if the MAF ground is reading above 0.009V.

It might be worth cleaning and inspecting the IAC and air regulator as well.