88 Burb, 5.7 TBI help needed

Our Suburban will not run with the MAP sensor plugged in with Vac or Plug.

If I remove either the Vac line or the ECM connector it will idle nicely, it wont take any load but will Idle. Have replaced the MAP twice so I know thats not it.


Have a scanner and there is only one code, a 44 O2 lean code the light only comes on after running for 5 or so minutes

When I disconned the Map I gett a 33 which would be normal, but when I do there is No 44

Any Ideas? Any help would be appreciated.

Also already done or replaced.
IAC
MAP
TPS
fuel Filter
Full tune up, Cap rotor wires plugs PCV etc.
Tried In-line fuel pump, (No Fuel pressure tester)

I am having the exact same problems. Only mine is sparatic. sometimes it happens sometimes it doesnt. I have also replaced just about everything i can think of, same motor, year, tbi and everything.HELP!!!

I am having the exact same problems. Only mine is sparatic. sometimes it happens sometimes it doesnt. I have also replaced just about everything i can think of, same motor, year, tbi and everything.HELP!!!

It was a bad fuel pump. only putting out 6lbs when it requires 9-12lbs