I have a 1995 Chevy Blazer. It runs rough at times and also has a problem of high RPMs when it starts up occasionally. Every couple of days when you start it up it will rev up to about 2500 RPMs. Any ideas?

 

rough idles are the stomach ache of vehicles. Almost anything can cause it, more information is needed to know what is going on. How much vaccuum pressure do you have?(should be around 17 in of Hg) Whats the fuel pressure and does it drop when you turn the key off? When was the last tune up done? Have the O2 sensors every been changed? how clean does the area around the intake by the butterfly valve look?(assuming you have CPI and not TBI)

 

Is it throwing any codes? There are a ton of posts on this problem Under Misfire could be one of a bunch of things. I had a similar problem which ended up being the Cylinder #1 Rockers were torqued down to Z vin specs instead of W vin specs but do some research on this site