Engine Missing (long)

[Josh Foster]

Hey List,

I need some ideas b/c my car just started missing.  I have a 92 SE-R w/ JWT
intake and E.S. motor mounts.  It acts like it is firing on 3 cylinders.
Here is a quick rundown: on Wed. of this week it started to miss at start-up
during my lunch hour and did so for about 1 minute.  At first, I just
thought is was the motor mounts causing it to vibrate more b/c the mounts
have only been installed about 3 weeks, and the Pop installed since last
Sat.  It acted fine until this morning when it started to miss when starting
it up first thing in the morning.  I had time to pull individual plug wires,
but they didn't seem to make a difference.  It started running correctly
after about 20 minutes.  I have not been able to the plugs b/c I had to get
to work.  I am trying to get an idea if this sounds like an ignition or fuel
problem.  When I installed the Pop, I have not put a filter on the AIV?
inlet that is on the exhaust manifold - I was researching the correct K&N
filter for it.  I did a tune-up about 3 months ago using OEM Nissan parts
for plugs (copper), wires, cap, rotor, & fuel filter.  I have some spare
injectors from a 93? SE-R (it was an auto), that I was going to have
cleaned; would it be worthwhile to install that fuel rail w/ injectors to
compare?

Any thoughts appreciated,

Josh