1990 MY Hesitation/ stumble of engine

[jrd1990zr1]

Was having this problem late last year, When at idle cold there seems to be a miss, like a bad wire. When the engine warms up the situation is not quite as bad but if you step on it the engine hesitates then seems to catch.

Over the winter I pulled the plenum, new set of GM wires, checked the coils. This Spring, same problem. Changed the injectors (FIC) about 9 years ago so they were supposed to be ethanol compliant and at the same time changed the plugs. This was about 30,000 miles ago. Car has 62,000 on it I don't drive it a lot each year.

I am at a loss, seems like next step is another set of plugs?

Can a set of FIC injectors go bad at about 30,000 miles?

Any suggestions on how to diagnose this issue? Is there a simple procedure to check the injectors without pulling the plenum?

Any suggestions would be appreciated. Thanks.