It’s surging while in drive or reverse with the brake on and when the accessories like heat and the light are turned on the surging gets worse I have replaced just about everything on vac system but the egr which is probably what’s wrong also temp sensor , iac valve a TBI rebuild I’m gonna pull egr soon and check it the whole power thing has me lost

 

Just to understand what has been done so far.

The TBI has been rebuilt?
The IAC valve has been replaced?

You can hold the rpm when you push just a little on the accelerator?

Check fuel pressure without and with electrical loads applied.