VG30E idles high

[pendulum]

I bought a 1990 SE V6 2WD from the estate of an old man who never drove it. The truck drove okay for the first few days I had it until it overheated because of a bad t-stat. After overheating, I drove it one more time to get it to my dads so I could work on it. It didn't overheat, but the temp gauge did get to about 3/4, and the idle came up to about 1500 for the last couple miles of the journey. The heater core had been bypassed when I got it. I've done the following maintenance/repairs:

New water pump
New timing belt
New dist. cap
New plugs (NGK BKR6EY gapped to 0.034)
New plug wires
New air filter
New radiator, radiator hoses, various coolant hoses (hardline to throttle body, heater hoses, etc)
Cleaned MAF

After the t-belt/wp job, the truck initially had a really bad idle, which lead me to do the following:

Oil/filter change
Almost all vacuum lines are new
Thoroughly cleaned throttle body
Discovered that the vac line to FPR was disconnected, so I took care of that.
New throttle body gasket
Adjust throttle cables

The idle is stable now, but it's anywhere from 1500rpm to 2k, depending on engine temp. Once the truck is warm, it idles right at 2000rpm and occasionally will have an episode of surging from 2k to 3k. This goes away on its own, and I can't reliably reproduce it. Disconnecting the IACV connector has no effect on the high idle or the surging. The truck drives the same whether IACV is connected or not, as well. I've checked the ECM for codes, and the results are 5 blinks from each LED while in Mode III ( https://www.youtube.com/watch?v=JWeWwI3qjYU )

I'm at my wits end. Can anyone think of anything I've missed?

[frapjap]

You might want to go back in and be sure that you aren't a tooth off on the timing belt. That could be a potential explanation to the engines behavior. However, before you go investing more time to go digging into it, check the timing with a light and see if there is a simple error and you can turn the distributor to clear it up.

[pendulum]

I ended up checking a bunch of things, including timing, and couldn't find a cause for the behavior so I just set the idle with the idle screw. I'm thinking that a previous "tech" may have adjusted the idle to cover up another issue. Still have a slight misfire, but it idles right at 750rpm now.