Hi. I´m new in this forum i´m from cental america, i have a pontiac firebird 2000, 3.8 c.c. 6cyl, and i have a problem, when my car is in 4th. gear at low rpms. ... the car starts to be have rare.... it is like i put gas and brake.... a few times.... like i give gas and let go de pedal.... but de rpms in te engine do not change...so i don´t think is the engine....when i put te 3thd gear.... the problem disapears.... help please....