88 Blazer random stalls

[Okie59]

Hoping someone can help figure this out somehow. Last spring my blazer was running rough with no power. A few people said cat converter, so cut that off and put exhaust on, made no difference. So took to mechanic and after a new intake gasket, reman dizzy and used throttle body, she was running good again, even better than before the problem started. Fuel regulator turned out to be the main issue. But after a couple weeks, it started random dying, with no warning it was going to stall. Sometimes it will stutter, but doesn't die, and maybe ses come on. When it does die, it's hard to restart, unless I let it sit a couple minutes.
I have replaced the IAC, put a delco ICM in the dizzy, with no improvement. The codes I pulled were 33 and 42. The mechanic did tell me he cleaned the egr and it may throw a code at times, but I haven't seen that code yet.
I'm not sure what to try next and can't just keep throwing parts on it. So any insight would be greatly appreciated.