You could also try cleaning the map sensor. That's a 50/50 on whether it will help or not. Sometimes it does sometimes it doesn't.
Also have you tried using an ohm meter to check the IAC and TPS? You can also check the map sensor with one too.
Also, and I am not sure if the 99 has one or not(I have a 4.7 03 and haven't worked on a 99 5.2). But see if it has an IAT sensor located in the intake air tube. Usually between the filter and TB. Also there may be a CTS(coolant temp sensor) that tells the ECM when the engine is cold and adjusts for it. All of these can be checked with an OHM meter.
It's possible it could be the EGR also.
I know it's a lot of stuff to check but you don't want to just throw parts at it. That can get VERY expensive.

To be honest what you are describing sounds more like a vac leak than a sensor problem.

Just to illustrate: I had a 95 S10. I replaced every sensor on it (IAT,CTS,TPS,IAT,o2,EGR,EGR solenoid,MAF,) and it still ran terrible. It would start and run great for about 20 minutes. So after a year of throwing parts at it I checked the injectors with a meter. Bingo! One was reading 1/4 of what the others were. Replaced it and all was good. That was an expensive lesson.

 

Did you do a reset again that may help

Always keep your replaced sensors as a backup they may still be good

 

Ok. So I just determined that the MAP sensor is ok. So that's not it.
I guess I will check for vac leaks. Is there any other effective way to search than carb cleaner?
Also, I noticed the one of the TB bolts are missing... possible culprit; leak under the TB? (just bought this truck 8 months ago, so the A-hole that traded it into the dealership I bought it from must have lost it.. I'll have to get another)


Its weird how when you take a vehicle for a test drive, all is perfect, then a couple months later, things just start.... happening. Like just a month ago, either the ABS pump went out, or one of the speed sensors, because suddenly the pump would run constantly, even with the key off and out! So I just pulled the fuse and called it good for now. It never fails that something goes wrong shortly after you buy a vehicle. Strange that I started having this idle and surging issue almost immediately after the ABS problem.

 

It sounds like a vacuum leak to me, too. And the missing bolt is quite possibly the cause.

You can listen for a leak using a piece of vacuum or fuel hose. Stick one end in your ear and "sniff" around with the other end until you hear the leak. Works great with exhaust leaks, too.