1999 Intrepid 3.2 120K

Was having multiple misfires. Replaced plenum gasket and lower intake gasket set. 2 new plug coils and 6 new plugs.

Problem: When starting the car, tach jumps up to 1700 rpm, then drops back down. (don't remember it doing this) Until the car warms up, it runs fine. After warming up and I'm going down the road without my foot on the gas and then I step on the gas, the tach goes up by about 500 rpm and then immediately drops back down to where it was....with no response for the first inch or so of additional gas pedal travel. If I floor it, there's a slight pause, and then it kicks in. While driving on the highway with my foot steadily on the gas, it seems okay. Any help?

I originally thought I had a fuel pump issue, so I relaced it. (Forgot to check tank for contaminants) (Sometimes I hear a noise from the fuel pump....like a heart beating) (Hope it's not related).

 

there is problems with throttle bodies building up excessive carbon and causing these concerns. carbon is build up and when started it may be stuck open a little causing high idle at first. check throttle cable and clean throttle body. add 1 bottle of chevron tecron to fuel tank to clean fuel njector and combustion chamber.