[malando]

Bought an 03 Carnival last week, K5 engine, 2.5ltr V6, 121000 klms (75000 miles), 5spd manual. Car sputters and runs rough in 2500 - 3500 rpm range in all gears. When I reset the computer it runs fine for about 10-15mins then goes rough again. Computer said it needed O2 sensors changed, (I've done that) Prob still happening, anyone had this problem, trying yo find a solution.

 

[Conglomerate]

Check air intakes for splits, loose connections etc.

 

[jlps]

Check the following ; clean the throttle body, replace pcv valve, if no misfire code came up skip checking the spark plus / wires / ignition coils. Next , fuel pump relay, fuel pump pressure and flow. Might need a serious fuel injector cleaning with either a repair shop fuel rail cleaning where they turn off your fuel pump and inject cleaner( like BG 44k ) into the fuel rail, or remove the injectors and send them to be cleaned and flow tested.