940?  Be sure to check the plug wire and the cap and rotor, also clean the throttle body

That probably means a bad maf or an air leak,  the maf meters the air coming In the engine,  if there is a leak, it throws the computer off, if you unplug it the computer substitutes a value and that could make it run better

http://volvoforums.com/forum/volvo-240-740-940-12/kick-down-cable-nuts-adjust-39702/

This link shows the rubber thing.   It has a blue circle drawn at the adjust nut

Went over all the vac lines,  poured a bucket of water on everything to see if it sucked some water and sputtered.  No luck.  I tried reading voltage on the connecctor that goes to the MAF.  None of the 6 plug holes had voltage going in.  Weird.   I need to see if my saab MAF has any voltage to it.   

as a last ditch effort  i unplugged the battery for hour.   Then rehooked it up.  when we restarted.  it ran normal again.  I can't believe it,   Will see how long this lasts.  SC

Yes. It has little code box,  but since cel was not on.  I figure nothing was recorded

As I type my random musings about this wacky Volvo problem,  sometimes inspiration results.   Last nite, took out the idle air valve motor thing and cleaned it.  Today the throbby idle was way less bad. Today,  disconnected  IAC,  Idle throb went down even more.  But it was still there, just like 10 or 20 rpm  up'er down.

Question:  if my car idles best with out AIC.  do I need it?. 
Am I wasting gas with IAC unplugged?
Does this point to another issue?  I got not CEL codes showing.  SC