99 gmc Sierra 1500, SES code: p0507?

[BILLBOB]

My ses light came on and is reading p0507 which is idle rpm higher than expected, it's idling about 1000rpm!! And it surges, like rpm will be at 900 then surge to 1200 and them repeat. Has a new fuel regulator, and cleaned mass air flow sensor, what could it be? I think it could be a vacuum leak, but how could I check? I don't have a smoke machine.

 

[PeteM]

Get a spray can of carb cleaner or brake cleaner and spray around all mating surfaces of your intake manifold.

Also spray around any hoses that you suspect may be sucking air.

When the engine RPM surges, you've found the leak.