Hey guys I've got a 95 f250 5.8 so I just replaced plugs and wires on my pickup because one of the wires had come in contact with my manifold and melted through but anyway I replaced the plugs while I was at it with ngk platinum plugs and it seems like I've got some power loss now could it be because of the plugs? Before I had motorcraft the mid grade ones

 

I also forgot to mention that I gapped the new plugs to 55 thousands Same as what I had my old ones gapped at

 

Six liter tuneup if you're going to gap that big.
http://fullsizebronco.com/forum/showthread.php?t=63592

 

I've done it

 

Nice. Not sure other than I keep hearing bad things about anything other than motor craft plugs etc etc. I've personally never had any problem but who knows.

 

I've heard that you should stick with motorcraft but u thought I'd give ngk a try

 

I run the generic Autolite coppers and have no problems

 

You mentioned that your old spark plug wire melted through, I am assuming it was causing a misfire? And assuming it was misfiring did you drive it for a long that way?
I learned the hard way that driving any significant distance with the spark misfire will pump raw gas from that cylinder into the catalytic converter and do bad things to it and cause back pressure issues and power loss.

 

i was driving down the road and it started to misfire and could smell gas I figured it was a bad plug or wires I took it strait home and to work the next morning then fixed it so maybe a total of 10 miles at most

 

I don't know what is considered acceptable for driving with a spark miss without damaging the cats but less then 20 miles home destroyed the driver side converter on my 99 mustang 4.6.... Looking at the front side of the cat it was completely pulverized from gas exploding in the honeycombs, literally no exhaust could pass through it and was forcing it through the EGR tube to the other side of the engine and with a significant loss of power.

 

I don't have a cat on it

 

I've run NGK's on my trucks, but not the platinum tipped ones. I would run the standard ones. Platinum is a big headache in these vintage engines.

Another thing to consider, did you unhook the battery and let it sit for a bit and the reconnect it and drive the truck? It maybe using old learned strategies and this MAY help.

I would try letting the PCM reset and adapt to new strategies and if that doesn't do the trick, pick up some Autolite Copper or Motorcraft Copper plugs and call it a day.

 

Lol, that pretty much eliminates that idea!

 

Just a random shot in the dark but it might be worth checking the timing, it isn't impossible for the distributor to move just a bit when messing with it and it isn't exactly a new truck so unless it's been done recently it be a good idea to do now.
My old F150 5.8 really came alive after setting the timing up to 12° advanced vs the 6° it was at stock. No cat's on that old beast either! Lol

 

I checked timing it seemed to be ok