I replaced my plugs on my truck ('97 1500 5.9 360 4x4) with Bosch Platinum +4.The truck ran great for about 50 miles and then began to mis fire almost to the point of stalling. I called the dealership and they recommended putting Chamion plugs back in. That fixed it. Has anyone experienced this problem. It bothers me a company would sell a plug that has such a terable effect on timing and not take them back because they have been USED even though they dont work.

 

I am running the Bosch +4 plugs in my 02 4.7L without any issue. I have about 2000 miles on them now and they are great. Just came back from a 500 quick trip across FL and had no problem.

I had champion plugs in before the Bosch +4's were put in.

Only thing I can see wrong with the plugs themselves is improper gap?

Maybe you got a bad wire(s)? When were they replaced last?
Maybe a wire has a bare spot or crack in it. When you put the plug wires back on were they in the EXACT spot they were before. They could be touching something they should not be.

How about the dist cap? Dirty connections or moisture can cause that. When was it last replaced?

Just some thoughts.

Good luck.