350 Not Running Right

[Chevy00]

Question for the experts: I have a 350 in my '69 C-10 and it is currently having a 'session' where it will not seem to run properly. The truck has picked up approx. 200 rpm at idle, seems to run rich (black smoke) and when getting on the pedal to put engine under load, acts like it is only running on 4-6 cylinders (sounds very flat & has no power at all). I have checked the wires to be sure that they were not arcing against the manifold & HEI unit seems to be tight, such that the timing hasn't changed. Problem surfaced after a spirited run at 70-75 mph, which wound the motor at 3500-3700 rpm for approx 5 minutes. Carb is an Edelbrock on top of Edelbrock RPM Performer Manifold. Ignition module was replaced 7/01. Any help would be appreciated