Hello. New to forum. Looking for a person or service center in the southeastern PA, Lansdale, area that is familiar with working on the supercharged engines. Mine stumbles when under medium to heavy acceleration, going up hills. Has new coils, trans serviced. Under normal throttle input car drives fine. Worse when car is warmed up after driving for awhile. Want someone competent to look at my car, that knows these engines. Have had problems in the past and cars damaged by garages. Never had any problems with this car in the past. Run premium fuel but wife has been known to put regular in it. Thanks.