4runner Stalling After Highway Driving

Good afternoon new friends,

I am the owner of a 1995 4runner with a little over 216,000 miles on it. She works great for the most part, but recently after driving on the highway the rpm while pulling up to stop goes to 500 RPM (normally sits from 650ish to 1,000 RPM) and then jumps up and down and then stalls (turning off the engine). Normally I can start her up easily, but after stalling, it takes about 2-3 times turning it over for her to start. I have put in fuel injector cleaner and have bought a new fuel filter (which I have not put in yet). She runs just fine on the streets and the problem only happens after highway driving.

I am trying to fix this problem with as little money spent as a possible, anyone have any ideas?

 

Don't have a 2nd gen but...

I would suspect the TPS (Throttle Position Sensor) or MAF air sensor or IAC and not fuel.

Computer either can't figure out where the throttle is or can't figure out how much air is coming in at idle or is trying to idle and the IAC isn't working right.

On my 3rd gen, it was hunting for idle with the AC on and a new throttle body which replaced the TPS and fixed everything. Ran fine at highway speeds but not so good at idle.

 

This might seem obvious, but it's worth checking all of your vacuum lines in the engine bay.

 

I just solved this same problem this weekend on my little sister’s Pathfinder. For her, it was just as @negusm above suggested, she had torn air intake boots between the MAF and the throttle body and was experiencing failure anytime air was allowed to pass into the tears. Driving slow, it wasn’t a big deal, but on the highway, or on bumps, it would result in the (worn-out) motor mounts allowing flex (and therefore unmetered airflow) in the intake hoses.

 

I checked the vacuum lines, and one was ripped. Thought it fixed the problem, but the RPM is still jumping once I get off the highway.

 

So, I replaced the throttle body sensor, cleaned out the throttle body, and the engine intake, and took it for a test drive. When I got off the highway it was still jumping from 450 to 850 rpm but it did not stall, so I suspect it did not fix the problem. I will try ordering the other 2 sensors.

 

Does this engine have an IAC? On the earlier 3rd gens, this is a major culprit as they lead very hard lives and the motor and valve go bad.

 

Check fuel pressure regulator for vacuum? It’s super easy takes 2 minutes.

 

On 2nd Gens, its a ISC, I will try and look at it now.

I ordered a AFM from a pick and pull and that could also be the problem.

 

I will look for into this! Thanks!

 

Good evening friends,

So, I replaced the AFM with a used one from a pick and pull and drove it for 70 miles including 2 highway trips. The ol girl, felt great during these trips, but today doing some city driving and lots of stops, she stalled once again, and I got her to start twice but stalled immediately. I was only 5 miles away from home and the entire time she was jumping from 450 to 900 and thankfully didnt stall at all the rest of the trip, but this is very concerning.