1986 slow speed lurching/chugging problem
 

Need some help, will list things I've done to fix at end of note, heres the complaint.Its a 4+3 and in second gear at low speed ( 25ish ) the car chugs or lurches as if in to high a gear, same in 3rd just at higher speed. To cruise in town I have to keep in first, at about 3500 RPM to avoid it. It does it around the 2000 RPM area. Been to a dealer 3 times, he's baffled. Not the end of the world to live with it but would prefer to fix it. I've replaced e-prom, new distributor cap, rotor, wires,plugs. Had an exhaust shop check pressure in front of and behind converter, cleaned throttle body, replaced fuel injectors, fuel filter. Anybody got a suggestion?

mine is doing a similar thing also but at around 1000-1300 rpm and its been diagnosed as the Crank Case Pressure Release Valve on the rocker cover...

lurching
 

make sure your spark plug wires are really seated on the cap, and pushed onto your plugs. This sounds like excessive gap either at the cap to coil, cap to wires, wires to plugs. Also check to see if the ground wire inside the distributor is indeed grounded. then do the same for the engine, then check to see if there's any vacuum leaks, check fuel pressure, and the little check valve/tee fitting on the left side of the distributor cap that goes to the cruise control isn't stuck open.
Check that the cannister purge valve plastic valve body isn't cracked and allowing the valve to flutter.
Then make sure the vacuum ball isn't cracked . Play with the ignition switch a little when it does this and see if it doesn't smooth out in certain positions.
Check out the oxygen sensor, and also make sure the maf connector is snugly inserted into the maf.

Thanks for the direction- wouldnt the cruise not work properly if the valve was stuck open. Not to sound inept but where is the canister located and how do I check the vacuum ball, I take it I can dismantle this canister?

Follow every vacuum hose and check them all for leaks. Has the timing been advanced any? Mine does that if i set mine to more than 10*.
benny