Won't hit a lick. 1st gen 99 V6 auto 4x4

Battery wires are good. I had a problem with them less than a year ago and got tired of fighting it so I had them replaced.

 

You've already double checked the grounds? Like physically removed and double checked?

You have a voltmeter? Could undo starter wires and hook up the voltmeter to ends while you crank, or have someone crank and see if starter is getting full voltage. Can pull starter and inspect/clean up/replace the plunger and contacts. Don't get a 'new' starter, will just be reman and not worth it. Your OEM starter is high quality.

 

I've done everything listed above with the exception of checking the plunger in the starter.

 

So you know you're getting full juice to the starter through the original wiring harness?

 

I don't know for sure if yours is the problem but mine was doing the same thing last year ,changed battery ,same intermittant no start and turned out to be the starter solenoid plunger and contacts were eaten away and barely making contact.It was very intermittant and I guess the extra voltage from a jump gave it enough extra juice to jump the contacts.That made it hard to trouble shoot.

Mine only had 85k miles and the Denso starter was fine, just a known bad design on these solenoids. Most people just change starters for $$$ but the solenoid plunger/contacts were like $10. PITA to get the starter out of a 4x4 but doable with patience .No starting problems since!

Here's what the plunger looked like,half eaten away and pitted and the contacts were just as bad.

 

Love seeing folks rebuilding these high quality parts that Toyota uses, instead of throwing on a POS mastercrap or something. That's one of the things that turned me onto Cruisers and then Yotas, the design and ability to rebuild many of the components with OEM 'rebuild kits'. Much, much better results.