***HELP Boosting issues 1997 JDM WRX ***
 

This is happening to my bro Scooby this only happens now and again car will jerk when boosting at top end of revs, have replace spark plug ,coil packs, fuel filter,and mass meter have a engine management light come on after jerking and before code 21 ,engine coolant temp sensor, will this sensor cause the jerking problem and backfire? ( guess that when the sensor is not working the car run rich?? ) he replace cam position sensor (secondhand, as other one got stolen:mad:! ) could this cause the problem also? or is anyone else have any idea what the problem could be thanks.:thumb:

someone?