ANY help will be appreciated....
1990 Caprice Hearse 307ci ~52G miles. Engine "surges" (service manual calls it "chuggles") at about 40mph and/or under moderate to heavy acceleration.
So here are the details:
Overheated a while ago. I assumed a hose burst. Turned out to be a leak in the intake manifold gasket (by cylinder #7).
Here are the parts replaced:
Cap, rotor, wires & Coil (all Blue Streak)
EST module (AC Delco)
Plugs (Bosch)
All coolant hoses, thermostat, coolant, rad cap (15 psi) (Stant)
Radiator (cleaned, tested at local shop)
Water pump
Fuel pump
Vapour canister filter
Coolant temperature sensor
Oil pressure sensor
O2 Sensor (Bosch)
Intake manifold gasket (bolts torqued to spec) (Fel-Pro)
Carb base gasket (Fel-Pro)
EGR
Valve & gasket (torqued to spec) (AC Delco)
Choke tube gasket (Fel-Pro)
PCV valve, valve cover grommet and hose to carb (FRAM)
The problem still exists. I have run out of ideas and what to test. BTW, the MAP sensor holds vacuum and the EGR is fine. Only codes I get from grounding the diagnostic connection are "13" and "14" (one long flash followed by short ones).
**ERROR CODES NO LONGER PRESENT*** 
Checked for vacuum leaks. Vacuum gauge holds steady at idle. Engine runs smoothly. Gas mileage has improved (marginally) since all repairs. Check engine light NOT on. Double checked all vacuum lines to make sure they are connected, and in the proper place.
I know this is a lot to read, but, like I said, I have run out of ideas.
Thank you for your time to read (and hopefully answer!)