Major misfire at idle and under load

I recently bought an 87 eta and it has a terrible misfire. The car idles around 500 rpm and has a heavy miss and barely wants to stay running. I'm assuming the idle control valve is functioning properly because when the misfiring gets really bad it bumps up the throttle to keep it running. I've changed the MAF sensor as well as the cap and rotor. Also the plugs and wires have been changed recently. I swapped out a TPS and CPS as well as the computer and none seemed to have an affect on it.

When accelerating the car coughs and bucks and can hardly accelerate. Here's the part that I don't quite understand and I'm hoping somebody could shed some light on it. The car will accelerate under very light throttle pretty well and when it starts missing I can let off the throttle and get back on it lightly and it will continue accelerating. Also when on the highway if I can keep it in 5th with the RPM's around 2100-2300 it will be perfectly smooth without a misfire. Also another symptom is that the car runs pretty well upon start up and progressively gets worse as it gets warm.

I've been reading that it could possibly be the harmonic balancer, but as I've looked at it it looks completely different from the one(it has teeth like a flywheel) that is problematic in other posts. Mine doesn't have teeth, it's just a smooth wheel with the front CPS sitting closely on.

Any help or suggestions would be greatly appreciated.