Dave, just don't know what to upgrade too... thought about the 79 series wagons but their motors are just as bad I hear. I do love the Hilux, the V6 auto seems to be the most reliable out of the lot of them, have contemplated on an engine conversion with 80 series front & rear diffs, which I am still thinking about.. it's all too hard!
Spewing lindlakebusa is it still under warranty? not sure if it would be your piston but does sound like a turbo failure
how is it getting too much boost, from a chip?