I JUST CHANGED MY SPARK PLUGS AND MY PARTS GUY GAVE ME DENSO IT-16 AND THE TRUCK RUNS LIKE ****. I TOLD HIM THAT U GUYS ARE RUNING DENSO IT-22. HE TOLD ME THERE IS NO DIFFRENCE BETWEEN THEM AND THE DENSO IT-16 ARE THE RIGHT ONES.

 

It all depends on your mods I have a 3 pound pulley so I run the IT 22's I think the IT 16's is for a stock truck I could be wrong

 

 

Well, there is a HUGE difference between IT16s and IT22s. IT16s are STOCK heat range plugs, and IT22s are 2 heat ranges colder. In fairness to the parts guy, if you just asked for Lightning plugs, the IT16 is listed as the stock application. However, I run IT20s for everything from stock to +4 psi. IT22s are for over +4 psi. I don't see why your truck would run poor though, unless you have more than stock boost and you already fried one of the IT16s.