when I drive and my rpm hits 20 miles an hour it gets stuck so I have to press on the accel a lil harder then it takes off quick! (happens somethings) what can be the problem? Also when I start my car in the morning or when its cold my rpm goes up and down a couple of times until it warms up. Anyone been through the same deal? help me out. please!!!

RPM's don't hit 20 mph are you saying they get stuck at 2000 RPM either way it sounds like the sending unit. As for your car reving up and down, when's the last time you changed your air filter, and it might just be the engine warming up or it might need an Idle adjustment. it hard to say with out hearing it.

might be my o2 sensor. I just got an engine replacement. I think the mechanic screw me over. after a while the engine light came on. Before when my engine was cold the engine would shake and the meter or rpm whatever it is goes up and down and sometimes to the point where it hits the bottom and shuts the car off. man this takes a lot of money away from hooking up my car!!! I was planning to get some seats ... -_-.