2000 Pontiac Montana Revs too high


My Montana (120000 miles)at times revs @3000 rpm. I can drive at 35 to 40 mph without touching the peddle. Sometimes it also slams into gear. I took it to dealer, charged me 189$ too tell me they couldn’t reproduce the problem. Frightening experience. Help


Does it always do this? How often? How long (both how long ago did it first do it and how long does it continue when it is doing it? Under what conditions? Any history of other repairs in the last year?


With a 7-year old van, it could be anything. But, I’m leaning towards an intermittent vacuum leak. Any air getting into the engine around the throttle body, with some EFI systems, will cause the idle to go up. To go up to 3000 rpm, it would have to be a large leak. This points me to the brake booster. Brake boosters are known to have weird leak problems when they are on their way out. Also, the PCV system may have a leak or a bad valve. The valve is cheap, usually about $5, and can be changed with just a pair of pliers.

Just a couple of ideas. Good luck.