I'm sorry, I thought more work had been done than that. That'* what I get for skimming.

I've experienced this symptom multiple times and it has always been ignition based for me, although I've never had your wastegate code. Still not a bad idea to pull a plug out and check the tip. I believe it will start looking orange if it is glazing over. I believe once I got down to a 3.5" pulley is when mine started glazing and it happened pretty quickly.

I also had a coil pack fail. If you have a scanner that will tell you which cylinders are misfiring you can see if they match up with a coil pack and also try swapping to see if the misfires follow the coil pack. If you do end up replacing them ever, stick with factory coil packs. Myself and other members have had issues with aftermarket coils, especially once you start pushing more boost. Factory ones seem to be the best.

Does the arm coming out of the supercharger and going to the BCS move freely? At one point mine started to seize up. I hit it with some PB Blaster right where it goes into the supercharger casing and let it soak, the next day it was moving smoothly and it'* been fine ever since (that was almost 3 years ago I believe).

If you blip the throttle can you see the arm go up and come right back down?

Look back to posts 7 and 8 in this thread and you will see I explained how to check functionality of the BCA and he confirmed it is working as described. That tell me the BCS and BCA are working. On the other hand, if he didn't check it exactly as I described, he could have a bad BCS.

It doesn't sound like too little/too much boost is the issue here. I see he did test with the SC belt off and there was no issue which means the issue is probably directly related to the car being under boost which is typically plugs, coils, wires, or fuel delivery.

He has new plugs and new wires, so I think we can rule those out. Even if the iridiums were glazing they should go a little while before that started in, if they were new, plus his setup seems to be mild enough to use them.

That leaves coil packs and fuel delivery. Any thing else I'm missing?

We have a thread on testing coil packs here: https://www.gmforum.com/trouble-shoo...-wires-278818/

If it wasn't for that P0243 code I would agree. I suspect he has a bad BCS and is getting full boost all the time.

You may be right, what would happen If i unplugged the bcs and took the car for a drive ?

I think I'm just going to get it scanned. There are just too many variables at play. It could easily be a fuel delivery problem. Maybe I had a bad plug/ wire and I replaced with another bad plug / wire out of box.

Definitely a good idea to scan for codes. You could be chasing a problem that is no longer there. If you do your own repairs you can buy a scanner on Ebay for around $30. They are very handy to have around.