94 SS running really rough when A/C on

I just recently had taken it in to have a computer diagnostic done by the dealer. They said the problem was the spider injection. I replaced it myself with the new nut kit and that made some improvement. It still has a slight miss to it at higher speeds, at lower speeds 40mph or less when you let off the pedal the engine revs up a couple hundred rpms. When the A/C is on it feels like its missing severely and running really rough. Anyone else experience this problem?

When you replaced the CPI and the Nutkit, did you pull your plugs? Typically when you have a lot of fuel dump like that the plugs get fouled and the EGR gets clogged up. So replace your plugs and clean the egr and see if that helps.

I failed to mention before that I also did a complete tune up after the change and cleaned the EGR because I thought that it might have been one of the problems. It still hasn't made no difference. Thanks for the reply.

have you tested your coil? battery and charging system? any of these will cause it aswell.

Check that all your vac lines are connected properly and that there are no dry rot or cracks in them. And when you did your spark plugs did you make sure that they were all gapped to .45?