Ford Repair: 3.0 liter valve ping, high octane fuel, valve job

Question
99 Ford Ranger 3.0 liter, flex fuel, 5 speed, 96,000 miles.  Valves ping terribly when engine is at full operating temperature and under a load, such as going up hill or full acceleration.  No pinging is heard when engine is cold.  Using high octane fuel helps some. With low octane the little engine sounds like a diesel.  I have cleaned M.A.F. sensor (really wasn't that dirty) New plugs and wires about 3,000 miles ago.  Have also re-torqued intake manifold bolts and checked and cleaned carbon from E.G.R. valve. Wasn't an excessive amount of carbon build up on the E.G.R. valve.  I can't help but think this is an fuel/air problem or emission component problem.  At least I'm hoping a valve job is not in the near future.  Any help at all is appreciated.

Answer
Pinging has nothing to do with valves.  It is a heat, timing, and fuel issue.  Ford has a service bulletin out for 3.0 rangers that says that a new coil pack and PCM reprogram will fix the problem.  Of course, that has to be done at a dealer.   You'll have to check with them for a cost, if I were to guess I'd say $300 for the whole procedure.  Hope this helps,
Jason