misses at startup almost goes away

[beeman212]

Car has a miss at startup and goes almost away after 5 min or so and drives great plenty of power.. has new head gaskets ,valve seals,intake gaskets ect... new plugs wires and tried 2 different coil pack/ICM setups with no change and checked all hoses for leaks ... any ideas...
Service engine light comes on once a month or so for cylinder 4 misfire....

[1oldman]

maybe a defective new plug wire or plug. have you swapped either one, one at a time on the number 4 cylinder? - BC

[beeman212]

Yea unfortunately I've tried different plugs and wires and I don't think its a spark issue I think its an injector .. I've ran a few tanks of gas with different kinds of injector cleaner and car seems to miss less while running gas with injector/fuel system treatment...
Tried chevron,lucas ,seafoam...
But its the only other thing I can think of but I'm not sure on how to check... when I put the engine back together after installing new head gaskets and all other gaskets and seals that came with the head gasket set with all the gaskets for everything including the supercharger and throttle body gasket.
So everything was methodicly cleaned and checked and recleaned and rechecked many times before and during Assembly everything was done by the book with everything done in sequence and toured to spec and then rechecked... car has 2000 miles since and hasn't used any fluids...
Changed head gasket due to car bubbling thru coolant overflow while running or just after shut off.. and car had a miss when I bought it so I figured the bubbling coolant tank and the miss be from bad head gasket but still does it...
Car has 180 deg thermostat and runs at 180-190 religiously never got hot since I bought car in February... did replace radiator first thing after bought car due to very small leak on driver side at or under top rad hose

[1oldman]

Check the resistance on the coil winding of the #4 cylinder and see if it's different from the rest of the injectors. Also could be a lifter, even a vacuum leak. Have you sprayed brake cleaner around the intake manifold at the #4 when it's cold? Be very careful as we wouldn't want you to set your prodigy on fire. I set my '92 on fire by accident once. - BC

[beeman212]

I did check the injectors and they where all nearly identical but didn't try spraying anything on it to check for leaks... kinda scared to try it but probly no other way to check huh?

[nos4blood70]

You should be fine spraying it with the brake clean, I wouldn't worry too much about it. It's a great way to check for vacuum leaks.

Could also swap around the injector itself.

[beeman212]

so update on this.... ive driven the car for atleast another 3000 miles since I last posted and now it misses when it wants to car can be cold or hot and its a 50/50 chance of missing and shows number 3/4 missing when it misses on my graph on my tech 2 scan tool.
car will start up and either miss or not and you can drive it long or short drives and it will either miss or not.
also not sure if it matters but my boost gauge with show like 8lbs of vacuum and after it warms up it will sit at 10lbs of vacuum all at idle .
does that mean I have a leak or is it supposed to be that way?