I have a subaru 2007 , 4 speed automatic transmission , there is a momentary lag (cold/warm about 2-3 seconds) between pressing the gas pedal and actual acceleration . It is very noticeable when It bothers me especially when trying to pass a car on the highway. I bought the car 9 month ago with 110k. The previous owner told me that he has changed a bunch of stuff including the timing belt, but so far everything he told me has been a lie! whats going on? should i be worried ?