Engine idling on 3 cylinders after overheat

[newtron]

I searched the forum , but never got a real answer.

I put a stud through my heat exchanger and ran it with the yellow light on for a little ways. Fixed the exchanger, but it now only idles on 3 cylinders and runs rough until you get up to cruising speed.

Did i cook a cylinder or is there something else?

 

[APEX 06]

Melt a sensor

 

[newtron]

what kind of sensor? sounds better than head gasket or engine

 

[TBay Sledhead]

Check if all plugs are firing, if they are do a compression test.