sup guys.. i have a 98 gsr with a 98 jdm spec motor. i will be swapping this motor into my itr soon. for the past few months. the car has been running kinda funny. when i drive the car in the morning, all is good. but after driving for 20 min or so, and once the car is warm. when i take the car out of gear and put it in neutral. the rpm's drop really low. the car feels like its going to die out.. then when im at a stoplight. the car shakes really bad. rpm's drop to like 500-700.. i dont know what it is.. been driving like this for a while. noone can figure out what it is..

any input would be appreciated..

thanks

 

try cleaning the throttle plate