mustang_kicker

Ok so on my 89 gtu i recently rebuilt the entire engine, replaced all the seals etc etc. Now i have it running pretty good, i have about 1200-1300 miles on the rebuilt engine. Ive been messing around with the timing alot, just today i took the eccentric shaft pully off and FINALLY found the marks for the timing and put some white paint on them so i could get that down. Well i got that done but it still has an idle problem. Once in the revs it runs great, no sputtering or missing or anything like that, but it just cant idle smooth, no matter what i adjust. Ive been playing with the screw on top of the throttle body, i assume that adjusts air intake at idle, and the screw on the actualy throttle butterfly which as far as i can tell adjusts fuel intake at idle. First of all im hoping someone can tell me the original settings for those 2 screws, i know the guy before me messed with them also so its not like i was blindly adjusting things. right now i have the idle high enough that it either idles between 1200 and 1500 rpm, bouncing slowly back and forth, or it sits around 800 rpm, but its a little rough but not bad. I havnt had any problems with it dieing at idle for a while now since the engine is moslty broken in i beleive. I am 99% sure all the vacuum lines are hooked up correctly and secure, since i did do the entire engine rebuild/removal/installation myself. Are there any common problem areas with the vacuum that would be a good place for me to start looking at ? Also i have a few bad exhaust leaks, i need to replace the whole system from the header back, would that have a significant effect such as idle problems ? From past experience i wouldnt think so but with a rotary i would not be surprised in the least if it did. When i first bought the car it had the same idle problem so i know it must be an external part problem ... my guess is the ratnest. One last peice of info here, when the idle is bouncing between 1200 and 1500 rpm the timing is spot on, as well as when i open the throttle it matches the description in the repair manual. But when it drops to around 800 rpm the timing mark moves counterclockwise about an inch, maybe more, and runs slightly rough but now too bad. Any advice is appreciated thanks guys.