If the engine itself didn't seem to follow the 1000 RPM drop on the tach, then I'd say you have an RPM signal or tachometer problem. If the engine did drop RPM (only going to know by sound frequency change), then I wouldn't worry about the tach. If you do have an RPM signal problem, then you'll need to figure out if it's the signal to the ECU, the ECU, or the signal to the tach. If it's the signal to the tach, then it's in the ignition control module (ignitor). If it's the signal to the ECU, then it's a sensor in the distributor. It shouldn't be the ECU since you have tried swapping ECU's and it did occur then too. If it's just the tach, then it won't affect the engine performance at all...

So I guess the next question that needs answered first is: Is the engine actually cutting out and/or dropping RPM, or is it just the tach cutting out and/or dropping RPM?

edit:
sensor in distributor that would affect RPM signal would be the CKP sensor (Crank Position Sensor).

 

been really busy this semester. I really appreciate your help btw.

the engine didnt follow the rpm drop. it looked like a second hand moving on an analog clock. Hopefully Ill have some time this weekend to swap out a fpr and check some wiring.