More idle issues...

OK, imagine a roller coaster that goes up and down, up and down, up and down... that is my idle - I dont understand what it could be. I had some vacuum issues - fixed. I ran the Lucas gas treatment stuff through the engine and it started running perfect, but now the idle does this. I plan on replacing the fuel filter as I am a relatively new owner of this little jewel, but does anyone else know what this could be? I had a freind with a Ford which did the same thing and he said it was some kind of idle sensor/regulator thing (i cant remember exactly).

Also, is there an official adjustment that needs to be done on the throttle cable? If that is out of whack, I imagine that could screw up the idle.

As usual any and all assistance is GREATLY appreciated!!!

ANNOYING
I have the same issue. It happens after the car has warmed up for a bit and then I put a load on it. Once the load has been applied it continues to oscillate idle speed whenever at idle. I recently took everything off to get at the injectors and have them rebuilt. Took off the throttle body, intake manifold, and fuel rail, plus disconnected a bunch of cables. After putting everything back together I neglected to replace the throttle body gasket, EGR gasket, and vacuum hoses (don't ask why I took some things apart, I just did because I wanted to take it apart and didn't follow the manual to a T).

After conferring with others and reading the manual I am guessing that it could be one of a few things:

1. One of the vacuum hoses has be compromised.
When I first disconnected the hoses, some of them had some blue flaky crud that had kind of glued them in place. I used a flathead to crack them loose and figured that they should be replaced but didn't because of a hasty repair. I also noticed that a vacuum nipple on the back of the intake manifold had a completely deteriorated plug on it. After plugging the hole with my finger while the engine was running I noticed a slowing down of the oscillating idle speed but it didn't completely stop it. My favorite guess is that it's a vacuum hose.

2. One of the gaskets that I didn't replace is allowing air into the vacuum system, compromising it.

3. On my truck it's labeled in the manual as the Idle Speed Control (ISC) servo. I'm hoping that it's not this because it's over a $200 fix. I've read about possibly cleaning the ISC servo and it's met with some success for others with other models of cars. We'll see if this works for me.

PLAN OF ATTACK
I'll be working one step at a time to resolve the problem and after I get my check in a few days. I'll purchase fresh vacuum hoses and try that, then I'll replace all the gaskets that I neglected before, then I'll try cleaning the ISC servo. If all methods fail then I'll do the ISC purchase and hopefully that'll be the end of it. I'll post further as I go.

*Note, I also replaced the fuel filter and cleaned off the distributor contacts at the same time I was getting at the injectors.
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FIXED
I finally got around to working on my car and seeing if I could get my idle issue resolved and that's when I discovered, hidden in the back of the engine, the electrical connector for the ISC was disconnected. DDDuurrrr....well you guessed it, once I plugged it back in, my idle issues disappeared and once again my car is running fine.
Although my issue was fixed with the simple solution of plugging the damn thing in , this could indicate on your engine that you have a faulty ISC servo or you have a bad electrical connection so that the ISC servo is not receiving power. Of course I would not rule out any of the other solutions that I had posted before but considering how my issue was resolved, I would definitely put my eye on the ISC servo being the root cause. Good luck!

Thanks for the info, one question - what does the ISC servo look like? There are several plugs and I dont want to just randomly start plugging and unplugging wires. If I could check out the servo and ever-so-gently clean it (as I am sure it's made of plastic which has probably gotten pretty brittle) maybe the problem will go away.