Doc, it only made the noise with the engine running and I only heard it for a few days. It was three quick, high-pitched beeps. It almost sounded ike an alarm on a wristwatch but I don't wear a watch and there was nothing in the truck that would makes a sound like that. I really doubt that the noise has anything to do with my problems but I thought I'd ask.
Sometimes, the engine will bog down and have no power and if you floor it sometimes (but not always) it will accelerate normally. One time (and only one time) it began to ping and knock when I was going up a steep hill. I originally thought that it may be the ESC module or knock sensor malfunctioning, retarding the timing (i think that it can retard the timing by as much as 20 degrees) but I'm not sure how to check these two items.
Right now, the truck is running normally again and I have no way of knwing when it will malfunction again. Occasionally, even when it's running good, I'll get a "flat spot" when I try to accelerate slowly. Also, I've noticed that when I'm sitting at idle for too long, the idle begins to drop and if I sit too long, it almost stalls (this just started to happen).
A year ago, the dealer replaced the TBI throttle plate because they said that the shaft was worn, knocking the TPS out of wack and causing some of the problems that I'm having now. When they changed the TBI throttle plate, the problems went away until November so I doubt that the throttle plate wasn't bad. This truck was a Surveyor's vehicle before I bought it so its been used pretty hard (and not maintained very well mechanically).
I haven't gotten much time to work on it the last few days (and besides, it's cold as a witch's tit), so I haven't been able to eliminate anything as a cause. I thought I'd put it out to the group to see what you can come up with (a bit of brain-storming if you will).