I have a 96 s10 blazer. fires up fine and drives great. However when you stick it in gear it is ready to go. It accelerates all the way up to 50 miles an hour on its own. It isn't flooring it but the rpm's, when in gear climb close to 3000. if you throw it in neutral it idles down and is fine, but as soon as you put it back in drive it wants to take off again. This problem happens about 95 percent of the time. if you stop at a light with the brakes on the truck acts like it wants to go. I have to put it in neutral to sit at a light. I have already checked the throttle cable and it is not sticking. Any clues???

 

bump bump

 

How many miles on the truck? Is the check engine light on? Does it idle at the same rpm's in neutral or drive? Have you done anything to the truck lately?

 

130k on the blazer. when you put it in nuetral the rpms are about 3k for a sec then idles down and stays there. if you put it in gear again it idles up. Nothing done to the truck, bone stock. service is all up to date.

 

try cleaning the idle speed motor first