installed new fuel pump,old one had 35 psi,new one now 3 weeks later is 38 psi,fuel filter is good,replaced pump relay too,it goes to very low idle at times has had miss fire on #2 cyl #6cly #8cyl..

fuel system is good now.. pressure is up to specs. timing chain or ignition module could be the next things to check. any crossed wires(correct firing order) ? wires to the ignition module kept clear of sparkplug wires? how many miles on engine?

sounds like a you need a new cap and rotor i had the same problem a month ago i changed everything fuel pump filter crank sensor spark plugs wires everything i could think of turns out it was the cap and rotor... that is if you have an lt1its a fun job...

Sounds like an Opti Spark going bad....fun job have to pull water pump and some other misc parts off longer job but not hard make sure to mark which plugs goto which cyclinder...