The idle on my 89 SSE was way too high (1500rpm). I checked the TPS voltage and came up with .54, which seemed ok to me. I went ahead & dropped it to .25 and the idle is now about 1000, much more liveable & easier to stop.
What is the spec for this? I always thought it was ok anywhere <1.0, but is .25 too low? I have found no vaccum leaks. What RPM are you guys pulling at idle?

i pull around 750 to 1000 at idle

TPS at idle (foot off gas) should be .38v-.42v. If it is reading higher & idle is high, check for a dirty/binding throttle plate that is not closing all the way before adjusting the TPS - plate should be fully closed at idle, all air goes through the IAC bypass.

At WOT it should read above 4.2 volts.

As to scan tools, there are a number of OTC 2000s on ebay right now - just make certain you get the cable (GM 12 pin) and cartridge (through your year) for your car.
http://search.ebay.com/ws/search/Sal...title=otc+2000. Right price is $25-$35

Lest we forget when dealing with problems in the vicinity of the TPS, along the lines of what Padgett is talking about......removing a nd cleaning the TB is a great idea if you haven't done so in the past 60k miles or so. Just make sure you remove the maf sensor first, and store it in a safe location before cleaning.