Well, check the following and make any adjustments you may need. Also, you should really post up on
www.probetalk.com . I assume you've been there already tho' since you've heard of the GM ignitor mod. Make sure you have all of the hoses in place. If the engine starts revs to about 2-3k then dies, look for a leak in the intake elbow. A crack or that large hose may be off (at the elbow and also at the rear valve cover)
Here are some write up I've done that I post up for most people to see:
If your idle fluctuates between 500-1500 rpm in a cyclical fashion, look for a crack or an air leak at the intake elbow (especially in the folds). The old rubber elbow tends to become brittle over time and crack. Like this:
http://www.rs-productions.com/RSP_Mo...t/DSC00021.JPG
If that is the case read Rick96PGT's write-up on silicone tape:
http://forums.probetalk.com/showthre...=silicone+tape
Try adjusting your throttle position sensor (TPS). You can do this by following the directions in the link provided. Also, the directions don't specify, but the fans should be off in diagnostic mode. So set the TPS at the point where the fans just turn off.
Link to Rick's TPS adjustment page:
http://www.rs-productions.com/RSP_Mo...ch/tps/tps.htm
Find the diagnostics box:
http://home.comcast.net/~mmunoz70/z/diagbox.jpg
Use a small paperclip to jump the TEN and GND (pic follows):
http://home.comcast.net/~mmunoz70/z/paperclip.jpg
Jumped diag box:
http://home.comcast.net/~mmunoz70/z/pinout.jpg
Then rotate the TPS (keep the screws slightly “draggy” to hold the TPS):
http://home.comcast.net/~mmunoz70/z/tps01.jpg