Loose connection perhaps or a wire oxidized up under the insulation and humidity or temperature or whatever causes it to change resistance slightly. On my '85, I would have starter issues when parked on a slight downhill slope. On flat or uphill, no issues at all. I figured instead of trying to find the source it was easier to put in a relay (that only needs 0.1 amps of current to turn on instead of 20 amps) and then that minor resistance issue would become a non-issue.

I agree, if I can't find an obvious connection problem, I will go the relay route. If actually rewiring the source and feed line to the switch is not too bad, I'll go that route.

I agree with 4crawler, I had a similar problem, spent weeks trying to trace it and in the end spent an hour putting in a relay and haven't had a problem since. By the way, if/when you go the relay route the standard 4 pin universal relays they sell at napa fit perfectly in the fusebox in the engine compartment, makes a clean looking installation.

Well, after tracing all the wiring and coming up with no obvious evidence or a short, I installed a relay per Roger's recommendation. I cut 4" off wire going to the #50 solenoid terminal and stripped the insulation off to find a nice green corrosion starting from the factory spade terminal and continuing about 3" up into the wire. Needless to say I had some voltage drop due to this corrosion and added resistance. I took susba's advice and installed the relay hidden in the fusebox on the passenger side fender of the engine bay, a nice clean install. I installed a 4 pin, 30amp headlight relay with a 30 amp fuse in line on the wire coming directly from the battery. Works flawlessly every time now, and I no longer have the itch to go buy a new Tacoma crew cab! Thanks for all the help folks! Now onto a timing chain install.