I have a 98 k2500 5.7,5 speed.While I was idleing at stop lights the tach jumped up to 1000 from 750 everything was turned off but it sounded like the a/c compressor kicking on.Later i was going to make a run to the hardware store and the abs & parking brake lights would not go off.The truck ran like s*it,it had to be restarted numerous times to milk home.About 3 hours later it started and ideled fine -I could not find anything that would stand out.I did notice the serp. belt needs to be changed-glazed but this is wierd s*it to me.Any ideas were to look?I have a 800 mile trip starting monday.Thanks