[piecesparts]

Try going to the basics and eliminate ALL of the outside influences on the motor. First set the timing on the motor (try setting it at 12 degrees BTDC)m second set the carb idles (I use a vacuum gauge, but adjust for a good smooth idle), then eleminate ANY smog garbage for controlling the tranny. Use the basic vacuum to the tranny modulator and that is all. Are you still trying to use the EGR valve? If so, this could be your problem. It may be stuck off of it's seat.

As for the fuel pump return being plugged. I tried removing my return and had a serious bogging problem, when I tried to accelrate hard in city driving (fuel overheating). I had installed an Edelbrock street fuel pump. I solved this by mounting a new bottom plate and added the return line back to the pump. I now have no coughing, sputtering, or bogging when I drive.

Take a look at your cap and rotor on the dizzy, my son's truck was runnung rough and when I opened it up the rotor was half gone.

Stock GM intake, which edelbrock carb are you using? Is it a replacement for the quadrajet or is it a 1406 design model. Have you check for a vacuum leak around the base of the carb?

When you put gas into the tank (at the 1/4 tank reading) how much gas are you putting in? A short bed truck's tank holds around 16 gallons and you can squeeze it to almost 17, if you work at it. I can usually run my tanks to dry before switching them, so there is a remote chance that your fuel tank sock is dirty or collapsed. This was a common problem in those years.