UPDATE:

the pinging came back, not as bad as before, but it's there for sure. don't know what would cause this still.

basic rundown is this...
new plugs and wires last may (about 17500 miles ago)
new fuel filter at the same time
new intake gaskets and injector seals (uppers and lowers) in late march (barely 1000 miles ago)
new timing chain that i just finished today

still have the pinging under heavy load (towing) and at high rpm's

everything that i have done only seem to act like a bandaid, and now i'm at a loss. everything i've done needed to be done, but i really don't want to keep pouring money into it without some results pretty soon.

the only things that i can think to check next are
fuel pump
o2 sensors
MAF

anyone have any suggestions or good ideas of what to check/do next? with summer coming up quick, i'm about to need it to tow the boat to the lake, and i really want to have it nailed by then. thanks for the help.

NOTE: all this has been on 91 octane