97 cavalier rpm spike
 

So I have been doing some work on my car new drumb brakes, boots and spark plugs today I take it out for a drive and while driving at 40 mph I put the car in neutral and the RPM's started climbing it got to 4,000 rpm and stayed there put it back to drive and they dropped to 2500 rpm's. When I come to a stop the rpm's stay at 2500 and it's hard to keep it at a complete stop.

Sometimes while at a stop the rpm gauge goes up and down going from 1000-2500 then back down below zero and all the dash lights come on but car doesn't stall out.

Anyone have any idea why it would be doing this and what the cause could be?

Vacuum leak from a vacuum line with a new crack from being bumped? dry rot?

I assume you gapped the plugs correctly?

Well I was stupid and didn't check the gap guy at auto store said they were pre gapped guess I should pull them and check em, not sure on the vacuum leak I don't hear anything that sounds like a leak.

Well i doubt the plug gap would be causing the rpm issues that bad, but always a good idea to check the gap when buying from the store. someone might have smashed one in or bent it up and returned it? or damage from shipping.

IS the throttle body level sticking? Is there a TPS sensor?

A vacuum leak would, like from a hose that you might have damaged would allow unmetered air in. check for cracks and hoses that are not connected.

Was the car fine before you got into the engine bay? check around where you were bumping into and stuff.