I've changed t stat clutch fan and truck still runs hot temp gauge will peg out but come back to 200 dges I've also flushed out the rad what else is there to do to correct the problem

 

Does it over heat on the highway or in traffic? How many miles? What motor?

 

Your radiator is probably plugged up and will require replacing. Warm up your truck and feel around the radiator, it will probably have a bunch of cold spots.
Steve

 

Make sure both radiator hoses are HOT. This not only indicate the water pump works, but also that the stat is open and water is circulating through the block and radiator

also, what engine is this?

 

is it actually overheating? Maybe the gauge going wacko

 

^^^^^ I concur. If its just showing erratic temps and not overheating, it could be the gauge or the sending unit

 

I had this problem with my 4.7 a while back. Replaced thermo, replace fan clutch, problem still there. Turns out one time while at the car wash, I had gotten the high pressure wand too close to the radiator and bent the fins (this was a very cheap/flimsy aftermarket radiator). I was surprised this because only about 1/3 of the fins were bent, so the air flow wasn't completely restricted. I could have spent the time to go and straighten them (the make a tool for this) but I just opted for a replacement radiator, they are very easy to swap out.