This is not a new problem since it has occurred twice before. First time after pulling into garage and putting gear into park....the engine starts to increase in rpm and there was no way to stop it......then it suddenly slowed down to normal rpm. This last time I pulled into the driveway after driving about 500 miles and as I approached the garage door I started to lift my foot off of the gas pedal and the engine surged (increased rpm) while still in gear. My response was to very quickly stomp on the brakes and just missed the garage door by inches. What is happening ? This is an 09 XFSC.

 

Sounds like a serious air leak, which this model is known to suffer from. Below the intercooler is a gasket of some kind known to leak and expensive to repair. Engine ECU should throw a code for lean mixture.

 

Well, I appreciate the leak theories and the reference to MAF sensors or the fuel filter/pump......but the dealer says that any of these would trigger a "check engine" light on the dash. I am paying more attention to this problem now and if it happens again .....back to the dealer.

 

Well, maybe, but some faults will not set the CEL ( the British call it a MIL).

The code might be recorded. The dealer should have tried to at least read the ECU.

I have had the engine rpm increase suddenly like yours, but followed by a no start, and just once. No codes and no repeat. The car started normally after this one fault, after leaving the car for a few hours.

No idea what this was, sorry.