i have a 74, 81, 86, 86, and had a 90 ram

if your mechanic didn't plug the egr, he might not have plugged other
parts -- or removed them for installation -- may have removed the engine
light or simply unplugged it (check behind the dash facing) -- so that you
would not get any indications of problems
definitely i would suspect the egr first, to egr amplifier, to egr solenoid,
ccegr if equipped also goes from egr then to amplifier which goes to carb
(so does solenoid) so look for hookups

if not,
i suspect you have done a lot of these things already -- not to insult your
intelligence but sometimes we forget the obvious, and you probably know how
to test (meters and guages not idiot light) but some readers may want to
know:

if you do not have a plastic tank, see if it runs smoother with more gas in
the tank -- could be sludge -- if this fixes the problem you are lucky --  
clean out the carb and keep enough gas in it until spring then clean out
your tank and check sending unit
check the plugs for oil buildup, other diagnostic problems such as
mechanical damage -- which could indicate motor not done right
pcv valve
old also be the carb -- you have probably adjusted the curb and fast idling
but check choke /carb springs work properly and none are missing -- holes or
places for spings that are not attached to springs, (take off top half,
check gasket, and clean -- holley 6280? -- check air temp sensor plugged in
and grounded), choke, temp guage, o2 sensor, fuel filter, fuel pump
(presuure problem?), gas filter, air filter or other components on the
intake portion of air filter pan, coil -- there are so many things

thermostat? put in boiling water -- it should open

check for vacuum leaks-- look for old hose, and make sure all hoses
connected properly, then if good, wd40 sections of hose at a time (which
temporarily seals a leak), and listen to the idling -- if it improves you
have found a leak, if nothing seems faulty here, get a tester/guage and
check anyway -- very common cause of idling rough

do you smell gas when it runs rough or does it seem to be choking from lack
of oxygen -- , fuel pump or could even be gas line?

if it idles rough, could also be timing -- check with timing light -- mark
with white pencil and look for slippage
could be distributor too -- you know to check firing order first before
removal of old one, then start with replacing the cap and rotor -- and do
the wires at the same time for good measure -- you will know to check at
night first and look for any sparks -- if yes, those wires are bad. keep the
ones in good shape in case you need one in a pinch,  and if you decide to
remove the distributor scribe or use a white pencil to mark the alignment
between the number one on cap and base so you can easily find
top-dead-centre later

best of luck

rachel

Definition: The EGR valve is the main emissions control component in the
exhaust gas recirculation system. The valve is located on the intake
manifold, and opens a small passageway between the exhaust and intake
manifold to allow a metered amount of exhaust to flow back into the
engine. This reduces combustion temperatures and helps control the
formation of oxides of nitrogen. The EGR valve is opened by the
application of vacuum to its control diaphragm. Some also require a
certain amount of exhaust back pressure before they'll open. On newer
vehicles, the valve is electronic and uses one or more solenoids or a
small stepper motor. The valve should remain closed while the engine is
cold and at idle. It should only open once the engine has warmed up and
is running at part-throttle. If the valve sticks shut (or is
disconnected), NOX emissions will soar and detonation will often result
(See Detonation and Spark Knock). If it sticks in the open position or
fails to close all the way, it acts like a vacuum leak resulting in a
rough idle, hesitation and possible stalling.