nichogenius

Hello, I'm new to these forums, but I figure if anyone can solve this problem it's you guys. I have a '91 Toyota Pickup 4WD 6 cyl. and it runs GREAT like most of these trucks do except for one small issue that's been bothering me. Sometimes the idling does something funny. It runs smoothly for a second, then it almost dies for a half second before picking back up, then repeating this cycle a second later. It almost sounds like there is someone stepping on the gas, then turning off the engine in rapid succession(except it never completely dies). As this doesn't seem to interfere with normal driving, I haven't really worried about it. It just sounds REALLY weird and has gotten me more than a few funny looks. I had my mechanic uncle take a look at it for a few minutes but he couldn't figure out what was causing it, but he didn't look into it too much either. I've heard it's a common problem with these trucks and I was wondering if there was a simple solution. All abnormalities stop as soon as any gas is applied. It seems to happen more often after it's warmed up for a bit. When it's running cold, this problem seems to happen less often.
Thanks for any help.