He needs to call Rich because internet troubleshooting cannot really solve his problem unless someone looks over the car.
Also, check the spark plugs when your're in boost shut down the ignition and see what the plugs are. Also do it for when it trying to stall.
One more thing, are you running new spark plugs NGK 7 series from Rich? If not, you might be overheating your plugs unless they're the right heat range.

 

it blew after 14psi with no tuning, boost cut didn't kick in at 10psi (stock map sensor) and 5 secs later cyl #4 blew a ringland.
Now running an LS, but need to do an alignment and then tune it to 13 psi.

 

 

I already got a bigger map sensor and will tune it conservatively. Might need to get ARP head studs as stock bolts like to stretch.

 

Think it was blowing out spark? Maybe shortening the gap would have helped. I guess the engine was owned though

 

6psi daily. Im fine with it. Atleast its safe. I kinda ----- footed it around town for awhile, and then got into it with a fox body tonight on the way home. Didnt seem to have any problems. Who knows, but seems to run fine now.