91 L89 idle stumble/stall
 

I have a 91 L89 6spd. w/ 34K miles with a major idle problem. It surges and stumbles at closed loop hot idle w/ w out air on. have cleaned throtle plate, isc motor, did a injector cleaning threw fuel rails, r@r egr valve 3 times(seals@ clean), no vac. leaks or vac. at idle. tried another O2 senser, tried another map. ck'd tps switch w/ ohm meter( smooth). replaced plugs(was due), scoped eng. ck'd timing. car runs great above idle. and runs great when cold(open loop). was in the tune-up bus. 12 years ago and no longer have my ob 1 tester, no trouble codes set. anyone out there have had a simular problem? cliffsurfs