1988 Calais 2.3 quad 4 idle/surging

[Rockett30]

2.3 quad 4 with a 5 speed manual transmission is having intermittent idle/surging problems. I just finished changing out the crank shaft. Got the car back together and it seemed to be running fine. Every so often (at least once a day) the car wont seem to be driving quite right. If I stop and let it idle, it will surge for a little while and eventually steady out. I did notice today that if the car is stopped and I hit the break hard, I can cause it to start surging again. I'm not getting any call out on the ECM and I haven't been able to find any signs of vaccuum leaks. Any one out there have any suggestions?