KA Stalling, and transmission question

I've got a 91 hatchback that is stalling on me alot. Once the car warms up to normal driving tempatures, it'll stall on me when ever I stop, or push in the clutch and let the rpms drop. Only way I can keep it from doing it is turning on the AC, but then every once and awhile the idle does drop down around to 300RPMs. It drops down like that 3 times in a row, then stop for about 20 seconds, then does it again.

I've done seafoam treat ment to my entire car, put new spark plugs in, did oil change, and the problem is still there. Any sugestions?

Also tranny question. It's a manuel tranny and I did a transmission flush, and ever since I've done that, it seems that when I shift between 2nd 3rd and some times forth, there is a bit of gear rubbing, as if the gear syncros where off slightly. My one friend said maybe I need an LSD additive for the transmission. I couldn't find out that information out anywhere. Anyone have any ideas?

Thanks
- Firewind

no you dont need an LSD additive. theres no such thing as an LSD in the transmission. its in the rear differential, hence the term limited slip DIFF. your friends dumb. dont take too much car advice from him.
if your grinding, thats just the way it goes. what did you use for tranny oil? if its too thin, it may induce early grinding.

as far as the stalling, try resetting your idle, check your tension on the throttle cable, check oxygen sensor, run the ECU for codes, and most of all, check ALL your vacuum hoses for leaks, especially the one coming out of the bottom of the valve sitting to the rear-passenger side of the valve cover(next to the EGR valve). that one seems to always break. but check them all. vacuum leaks are common stalling causes.

I'll check for leaks tonight then.

The reason he said anything about an LSD additive, is that was recommended on his 06 WRX.

For tranny fuild it was 80W-90 gear oil.

well thats the right fluid...your tranny might be on its way out. the reason he needs LSD fluid is because he has 3 diffs- one in the tranny controlling the front wheels, the center diff, and the rear diff. theres no reason to have an LSD by the wheels not even being driven.