Well I got a issue with my 86 ls monte with the 4.3 well I've rebuilt the Tbi and and new pump and strainer and filter.But now when it gets up to about 2000 rpm and let off it either shuts off or almost dies. I've checked for vacuum leaks and don't have any kinda wonderin what else it could be

 

Sounds like the idle air control (IAC) sensor. Does the check engine light come on? Advance and Auto Zone do the free check engine light diagnostic. What kind of shape is your distributor/cap/button/plugs/wires in?

 

New cap rotor button plugs and wires but its not showing a light

 

Been a while since I've tinkered on an older engine (the TBI's and carb-ed ones to be specific).

When checking for vac leaks, did you do it visually or with a gauge?
If it was just checking lines, use a gauge or get a can of starting fluid. With the car running, mist the starting fluid around, if you have a vac leak, it will suck it up and the idle will make a change.

Other things I can think of:
- Clogged fuel filter
- Bad fuel (if it's old it may be gumming up)
- Pinched fuel line (when you get to higher RPMs, it's obstructing proper flow)
- Clogged cat (normally does not cause a shut down, one way to test, remove the O2 sensors that are before the CAT and let the exhaust vent that way, just for a short test)

Just some thoughts.... Best of luck!!

 

Fuel lines are new and so is filter and I used starting fluid and the cat was removed also I forgot to mention a new tank and new gas I may run a gallon or two of the turbo blue to c if it will help any

 

I mentioned the fuel line bit as I new a guy with an El Camino who thought he had to replace a fuel tank due to "sludge" in it. He bought a racing fuel cell and as he was removing the gas tank, he found he had a pinched fuel line that was the source of all his issues. But he continued on and put the fuel cell in the bed.

Unusual situation, but one to consider (even with new lines, a bad bend can cause all sorts of grief).

As long as you are running fresh 87+ octane, no need to get any "special" fuel.

Best of luck man. It will probably result in something simple (most weird issues normally do).

 

| Repair Guides | Electronic Engine Control Systems | Throttle Body Fuel Injection (tbi) | AutoZone.com

Here, try this link. Its for celebrity and century but the tbi is the same as your 4.3. From what I gathered from this, it sounds like the throttle positioning sensor or idle air sensor, but it could be any number of things. What gets me is the absence of the check engine light in all of this.

 

Well I took the new idle air control air and put the old one back in and what would u no it's running like a top. Who would of thought a new part gone bad lol thanks for the input really appreciate it

 

Idle air control valve man I can't type today