New user w/ perplexing problems

Ok that seems about right then being double. As far as the high idle you are probably correct on the worn throttle body. While I was cleaning and inspecting I noticed just a little bit of light shining through the butterfly valve when I held it closed.

 

It also just takes some time for the ECM to re learn things after a reset/battery disconnect (or replacement in your case). I was chasing a high idle and after numerous attempts, it turned out that my throttle cable was over-tightened a little. But it also took time after resetting the ECM for it to drop to around 750rpm once it was warmed up, etc..

 

OP, you are all over it and congratulations.

 

Pics of the bad ECM! BAD ECM BAD! Looks brand new to me

 

Those electrolytic capacitors can look good but be bad. The cylinder shaped things, like C120, C107, C102, C104, C807, and one other. I counted 6. They dry out inside after 20+ years. It's a bit hard to test them in circuit unless you have an ESR meter, but even then you sometimes can't test them in circuit. If you take them out you can test them with a multimeter with a capacitor test function, but if you are going to do that you could just replace them and see if it works afterward.

 

Right, it's all so complex. Even if I did go through all the trouble to learn how to diagnose and repair these electronics, I don't even have a soldering iron or the proper tools to do the job. It makes my damn head hurt just trying to understand these complexities! What's even more perplexing is the ECM I used to replace this one looked like it had been sitting outside for about 10 years! Rust all over the damn thing, and it works better than this one that looks almost shiny brand new

 

How many miles on your truck?

The capacitors generate heat when in use, and that dries them out over time, but it still takes many years. The new ECM may have less miles on it, so sitting outside wasn't really causing any damage. I assume you mean the truck was outside, but the ECM was still tucked under the dash somewhat protected from the elements?

This all assumes the capacitors were the problem. It could very well be some other component failed. And those are random chance. An electronic part might last 200k miles and 20 years while the same part on another car might last twice as long before failing.

 

178k miles on the truck. Yea I understand that the wear and tear on these kind of things vary greatly due to a wide range of factors. Just so strange to me.

The ECM I used to replace was one I got from a guy that literally has a Tacoma graveyard in his front and side yard. All the parts and pieces he’s accumulated over the years are littering his outdoor storage garage. Shelves and shelves of things like ECM, starters, alternators just to name a few that I noticed at first glance. Not inside of any vehicle. He’s stripped all the trucks of their parts and stored them there. No garage door no climate control and a dirt floor. Many of the parts are covered in mud and muck. So they are less than ideal to say the least