I've tracked down my sluggish running problem to cylinder #4 missing.
Using a laser temp gun, all header pipes at the exhaust manifold were 600 degrees F, cylinder 4 was only 300 degrees F. Either it is not getting spark or fuel. It is missing at idle and WOT.

What I've checked so far:
all cylinders compression OK
removed valve cover, all valves moving OK
new ignition mod.
new coil
new plugs
new wires
swapped injector #4 with injector #3, the miss stayed at #4

I still haven't fixed the issue.
Here are my possible questions:

Could the ECM be bad and not sending spark or fuel signal to cylinder #4?
Is there any way to see if injector #4 is getting signal without a oscilloscope?

Any other ideas?

 

You need to check for spark at that plug and get a noid light and check for injector pulse at the injector.

 

My new set of plugs had a problem. Plug #4 was cracked and not sparking when under compression.

I guess always check the easy stuff first.

 

Sounds good enough !!

 

Just for future reference thirdgens use batch fire systems so the computer doesn't tell a specific injector to fire, it tells ALL of them to fire.

 

Except for the later Buicks, which are SFI.