Thanks for all the advice. Work covered me up the last few days, so I haven't had a chance to pull the plugs yet, but I'm going to get after it this weekend.

Drcoffee - I have a cheaper scan tool, but I do think it shows a reading for the MAF - I'll report back on that. I have definitely tried seafoam, that may buy me a week or two, but nothing that results in a permanent fix.

OopsIbrokeit - I have a small leak in my radiator that I have to keep an eye on. I'll need to replace the radiator soon - it's still original. I keep an eye on the expansion tank, and have to add maybe 1 qt every 500-1000 miles. Ironically, I just finished a head gasket on my sons 1996 Tacoma. Thankfully it's the 3rz 4 banger...... Turned out the head was cracked, but she's back together now and on the road. It wasn't too bad....but I sure hope that's not what I'm looking at. I do my own regular oil changes, and haven't noticed any coolant in the oil or anything that would make me concerned. It never runs hot. When you say "look at the wiring harness and check voltages" - can you be a little more specific?? I have a good multimeter and I'm not afraid to use it, I'm just not sure what I'm checking. (My favorite car to wrench on is my 1986 Jeep CJ7 - no computer, CELs, etc. It's simpler than most lawnmowers

MikeinNH - Thanks! It's actually the downstream sensor that keeps failing......(about 6 times now)......and then occasionally the upstream (maybe 2x since Ive owned it). Could that still be a relay issue?? I'm still not really clear how to "test" an O2 sensor. Do you mean with a scan tool?? Or multimeter??

Thanks guys for all the good info - I should have an update this weekend after I dig into it.