Today my 96 tahoe kept going up 1500 rpm about every minute. The only time it stopped was when I was accelerating and it would be at 1500 consistently. Anyone know what could be happening? It was very hot out, not sure if that would affect anything.

 

When does this occur? While driving or are you saying this happens when it's in Park?

 

it is happenening constantly. the only time it stops is when i'm on the gas. So it is doing it in park, but also while stopped at stoplights and coasting.

 

So it's at idle?

Most engines use an Idle Air control, yours could be dirty, or worn out. It's a part that controls air flow at idle/start up.

https://www.google.com/search?q=1996...utf-8&oe=utf-8

But I'm no expert, so don't go run to buy things without another opinion.

 

This was happening yesterday, I just went out and started it and it wasn't reving. Everthing seemed normal, it idles at around 1100. I did recently have the air filter out. and it was really hot out when I was driving. Most times I've ever started the rpms will go to around 2000 for a few seconds then they will drop back down. The mileage is over 240,000, as far as I know it has the original motor. 5.7L Vortec