My 2.5 Revo has decided to run hot (around 280 with tempgun). I've used the tuning guide and leaned out, no help. Then went slightly rich and still to hot. I've ran it like that twice, hope it didn't cook the engine. I first noticed it because the truck was running fine then just slowed. Put the temp gun on it and got a 290 reading. Of course shut ti off right away and let it cool down. Doesn't seen to have a leak around the header. Could the resonator cause it? The exhaust (resonator) reads 200 when I check it.