But that doesn't make it right.
OK... I'm new here. I just got a '99 Firechicken 3.8 efi with the same #4 idle miss that occasionally throws a code. Like another poster, mine's also really bad at start up and seems to smooth out some as the engine gets closer to operating temp. Even then, if you creep the throttle forward from a full stop the engine stumbles and then surges into passing gear, kinda like a carbureted engine with a sticking float. But heavy throttle from a full stop gives smooth acceleration.
I'm just getting started with the elimination process (wires, injector, ign pak, fuel pressure, etc.) and am interested to see how the OP's problem plays out. I'll definitely post back if I find a cure for mine. ~FH