tree magnet

Hello
I have a 92 5l gt That I just bought. It has magnaflow headers and exhaust. but is stock other then that.
It 2500rpm it looses power and backfires a bit if I push it after that rpm range.
I have replaced the airfilter dist. cap, rotor plug wires, and am about to do the plugs. The plugs are whiteish on the ends and my book says in these conditions I should replace them with a colder heat range plug!

Question 1- could the plugs be causing my powerloss issue? if not what should I check next?

Question 2- I was under the understanding that when you install headers you should lower the heat range on the plugs. How much under stock plugs should I go? What plugs should I use? It has bosch platinum plugs now which I don't care much for?

dawson1112

Whitish plugs are not the source of the problem they are a symptom.
It could be a bad/dirty MAF, bad or disconnected 02 sensors, failing fuel pump etc etc.

Do a diagnostic and get the codes that are stored in the ecm. My guess is that your running very lean in the air/fuel mix.