I had a 1991 3.0 V6. The truck had a rod knock when I bought it, but I pulled the 3.0 out and had it rebuilt by a well known machine shop (the same shop, incidentally, that did all of the 3.0 rebuilds for the local dealerships during the headgasket recall campaign). Rebuilt it using forged crank and piston rods from a 3VZ-FE. Rock Products .030 over pistons, new toyota oil pump, rod and crank bearings, water pump, headgaskets, ARP head studs. Basically I spared no expense trying to make a long lasting motor.
Anything that was even questionable I replaced with new OEM where possible.
Drove the truck for 4 years, and about 50,000 miles with regular oil changes, and it threw a rod........
I won't do another 3.slo ever again. I wish I would have just swapped in a 5VZ-FE instead.