this car is a 3.1 auto when starting the car it revs up to 1500 RPM then gradually drops to 1000 then to 600 this takes 3 0r 4 minutes at 6 degree c. here come but ... when putting in gear and stepping on the gas it hesitates for a split second .....but #2 when the temp reaches the operating temp. or once you run it for about 15 min. car is ok . the head gasket where replaced 300 k ago .thanks mike B.