1991 K5 TBI 350 with SM465. One out of five times the idle will seem to fall out when taking it out of gear and coming to a stop. It feels like a misfire. It will correct itself after about 5 seconds, can usually correct it a little quicker by revving. Less commonly, it will do this going into first gear from a stop and I'll need to give it gas to come out of it. It never actually dies. It doesn't matter if it's hot or cold. I have rebuilt the throttle body with new injectors, replaced IAC and MAPS, and repaired several vacuum leaks in lines. Any other suggestions?