LT1 - optispark, fuel pump, or what?

I have a 1994 RMW. It had 141K on it when I bought it and now has between 180-190K. It has always run perfectly. Yesterday I took it out to eat and it ran fine but when I returned home it started running really badly. Symptom is a heavy misfire (multiple cylinders) whenever I give it more than say, 10 to 20% throttle. It starts bucking and chugging. My buddy says it is spark knocking a lot but his hearing is much better than mine. It starts fine and idles OK with maybe a hint of a miss. It makes no difference whether hot or cold. When this started it was very low on gas but not  enough to put the low fuel light on.I put a few gallons of fuel in it and it made no difference.

Since I owned it I have replaced plugs and wires, coil, EGR and TPS, various vacuum lines, intake gaskets, O2 sensors, fuel filter (twice) and etc.

So, I'm thinking either the fuel pressure is low or the optispark is finally giving up. I have not done any debugging. I have a good scanner that I can use but it is not lighting the CEL. Next weekend I will test the fuel pressure but if that is good I am going to have to start guessing. I'm kind of up against it because it is due for its emission test (always passes) and I have postponed it once due  to lack of time and now I need to get the thing running right or surrender the tags. If it is something horrible I might think about trading up to a better wagon but it's pretty nice.

Any ideas?

fuel pressure is where i,d start. mebbe a filter,...

The symptoms you describe seem to be more related to ignition than fuel, but it's difficult to "pin down " on a forum. If you have 185K on yours, and the distributor cap and rotor are original, then, well, that's a lot of miles!
I have a problem that I've decided is a bad fuel pump, but it acts strange. It runs perfectly for 10 minutes to an hour, then goes "way lean", (un-driveable) and barely idles, then shuts off. After 5 minutes, it will restart, and run normally for some undetermined period of time, then go through the same thing. A fuel filter change didn't help. I said it acts strange, because from my experience, when in-tank pumps quit, they usually don't start, although the rubber mallet trick often works. With 180K on it, I think it's time for a new pump, anyway. So in two days I'm installing a new pump and fuel pressure regulator. Oh, how I'm looking forward to that!! :-).

The link below might be helpful, starting at my post just over halfway down. Check your coil wire and ground on the front of the cylinder head (behind the coil).

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Well, I put a new AC/Delco coil on it not long ago and I know it is well-grounded. So that shouldn't be the problem.

Check your fuel pressure at idle and under load. What was the weather like when your problems started? (Was it damp or wet out?). If the fuel pressure checks out OK...open the hood at night with the engine running. Listen/look for arching, pay particular attention to the coil wire. (Is it shorting out?).

Your Opti could be the issue, however I would check the other items before jumping to that conclusion. I have a car with 380K miles on it...and its still running the original opti and cap/rotor.