i have a 02 2.2 noneco auto i blew the moter and swaped a five speed with new moter 2.2 noneco all i did was drop moter and tranny ( ithink its the izuzi trans ) in jump the p/n switch and plug all the sensors in i am having a problem with when i stop at a stop light the rpms bounce up and down btween 3000 and 500 it bounces a couple times then it will shut off thats problem 1, i have checked all the vac lines all is good . second is when i leave a light at high rpm and shift in to second the car acks like it has a studder and it does it bad makes the car jump . i am still runing all the automatic stuff ecu bcm and harness should have switched anything to a 5 speed ecu . or should i just find some way to flash my ecu . problems are not all the time just some times

have you checked the Idle Air Control Valve?