I have a 91  ea82  autovagen  ,  that is  spfi ,  just did a tune up  / plugs wires cap rotor /  on it 5 k  miles ago .  running great ,  yesterday it started idling rough. and the acceleration  off idle is sluggish .  after  1500 rpm is does ok .  it hesitates at the low end .  it will do 65 mph  no problem .    im thinking egr , or mabe  idle air circuit ?  . the check engine light is on now too .

I'd be surprised if it were egr. The only idle air failure I had just killed idle. The codes might be a big help.

I would check for fault codes and make sure to fix any first. The coolant temp sensor and connector are known problems on these engines too, so get a look at those. Next I would check for a bad spot in the throttle position sensor just off idle. This won't usually set a code but it can cause a bad stumble.

im thinking a different problem  now....  driving it to work today , I was using the  defrost.  when I accelerated   the ducts went  from defrost to vent .  I was only at 1/4 on the throttle. and it was  instantly . ill have to get the propane out and see if I can find it. im sure its intake gaskets. 

There should be a check valve in the vacuum line to the vacuum reservoir that supplies those vent actuators.

 

The check valve could be bad, or there is a leak. That could also explain crummy idle.