My oil is full and no exhaust leak, and I get alot of heat out the tail pipe because the mud flap is burning away (not on fire).

 

I run 89 although the manual says only need to run 87. The reason I run 89 is because the previous owner said he ran 87 in it on a trip and it didn't seem to run right but has always ran great with the 89 since new.

 

I found a great write up on Octane. Cut and paste the following to your address bar. http://europeancarweb.com/tech/0503ec_techboost/

 

If your truck is pinging, and you need to run higher octane fuel check for a blow intake gasket. You can do this by looking down the tb(engine off) Your looking for pools of oil on the floor of the intake manifold. If there is oil there a very good chance the gasket is bad and that is the source of most of the pinging.