04 Tundra V6 Roaming Misfire
 

I have a 2004 Tundra V6 with a strange misfire problem. When the misfire started I ran the codes and got a Cyl 6 misfire. I changed the plugs and wires with NGK dual electrode plugs. The truck ran fine for a few days then the misfire started again and I got the same Cyl 6 misfire code. I cleared the codes and the truck ran fine for a few minutes then the misfire returned along with the CEL. However when I ran the codes this time I am now getting a Cyl 3 misfire code. The truck is an automatic with 280K on it. Any suggestions would be greatly appreciated.

Another added wrinkle. If you lightly and gradually accelerate, there is no misfire and the CEL is not triggered. Moderate to hard acceleration, the misfire returns and the CEL is triggered.