Deposits on the intake valves due to age and a lot of bad gas over the years (a common VW problem);  bad injector spray pattern due to clogging;  bad spark plug wires (is the problem worse if the roads are wet?);   old or worn out spark plugs, or leaking spark plugs (haven't seen that in years, but it used to cause symptoms like this);  bad distributor cap (also worse in the wet).

James
Ottawa, ON
'91 Vanagon Multivan Westfalia;  formerly had '83 Rabbit L, and '94 Golf diesel and '95 Golf 2.0L

> Date: Thu, 16 Jan 2014 21:22:44 -0600
> From: jrodgers113@GMAIL.COM
> Subject: Volksiebus - 88 Transporter  - Rough Running Engine
> To: vanagon@GERRY.VANAGON.COM
> 
> Rough engine - the latest pita I'm having to deal with on a string of
> many!! I'm on a roll!!
> 
> Ok - hot or cold - engine starts and idles well.
> 
> Conditions - ISV disconnected due to Idle issues
> O2 Sensor Disconnected to put ECU in default mode.
> 
> Cold engine: starts easily, idles easily, but upon attempted
> acceleration it bucks, kicks, snorts, hiccups, coughs - finally
> smoothing out at speed.
> 
> Warm engine: starts easily, idles easily, but upon attempted
> acceleration it  bucks, kicks, snorts, hiccups, coughs - finally
> smoothing out at speed.  Only the bucking isn't quite so bad. Occurs
> mostly on the initial acceleration after idling successful.
> 
> Suspicion: Throttle body switches out of limits and need adjusting.
> 
> Anyone have any ideas about this?
> 
> Thanks,
> 
> John