3.1 motor surge

i have a 91 gp with the 3.1 that that motor sometimes wont run and surges at high rpm like a vacum leak but there is none took to mec and he scaned it and all checks out he can not isolate the problem checked egr and all that has anyone exp anything like this help please

remove the IAC valve from the throttle body and see if it's covered in brown or black crud. Clean the tip of it and the bore it rides in with spray carb cleaner and see if it fixes your surge problem.

remove the IAC valve from the throttle body and see if it's covered in brown or black crud. Clean the tip of it and the bore it rides in with spray carb cleaner and see if it fixes your surge problem.
been done and total replaced iac and removed and cleaned intirer throttle body

I know it seems unrelated, but does your heater control switch from heat to vent to floor etc, or is it stuck half on defrost and half to the floor? The HVAC is vacuum powered, and if the vacuum line running from the engine, through the firewall and to heater control head is cracked, you will also get an engine stumble from the vacuum leak.

I know it seems unrelated, but does your heater control switch from heat to vent to floor etc, or is it stuck half on defrost and half to the floor? The HVAC is vacuum powered, and if the vacuum line running from the engine, through the firewall and to heater control head is cracked, you will also get an engine stumble from the vacuum leak.
NOT REALLY THATS A GOOD IDEA THAT NEVER ENTERED MY MIND BUT THATS WHAT I HAVE THOUGHT IT WAS ALL A LONG I AM TRYING TO FIX THIS LONG DISTANCE MY SON HAS THE CAR IN NEM MEXICO & I AM IN OKLAHOMA THE SHOPS THEY HAVE DOWN THERE DONT SEEM TO BE UP TO SPEED SO ITS LOOKING LIKE A ROAD TRIP FOR ME THANKS FOR THE IDEA HOPE IT SHEADS SOME LITE ON THE MATTER AND L WILL LET YOU KNOW HOW IT COMES OUT THANKS PAUL....

I Wanted To Thank Everyone For The Tips And Let You All Know That A New Computor Was What It Needed Even After It Checked Out We Still Tried It And That Fixed The Problem Apparently It Has Been Bad For A While Because The Car Runs Better Know Than It Ever Did You Cant Even Hear It Run Know Smooth As Glass Anyway Thanks For The Help Paul....