Ok this happend after the car sat for about a month and a half. Almost all the time now, the rpm is about 400-500 lower than what its suppose to be. At idle the rpm is zero, instead of the normal rpm. So it starts from zero instead of 400 or 500 and is always a little low by that much. Sometimes after I get off the highway and the rpm has been high for sometime, when i come back to idle, its ok. What could the problem be?

 

 

check for corrosion on your distributor wires just take the cap off and check the wires there spray some wd40 oin them. and spray the connectors infront of the distributor. you might have corrosion some where in that area.

 

Having same problem just a little reverse, idles a 1500 and at 60 in fifth it's at 2500 when normally at 3000, been told stock tachs just suck and using an aftermarket will be more accurate, but i personally i'm just living with it.

 

stock tachs are off, if your tach is bouncing all over the place though, your ignitor is bad