Timing on the M103 is controlled by the EZL module and position sensor on the crankshaft damper and is not adjustable by rotating the distributor, which on the M103 is just a secondary distribution system at the front of the head driven by the cam, but I would certainly recommend a timing check. The value is listed on the emission/tuneup label, and my '88 is 9 degrees BTC. If the timing is in spec the EZL and crankshaft position sensor are probably okay.

There may be multiple problems here, but you can start by checking the ignition timing and setting the basic mixture adjustment properly. Print out the following web pages, read them thoroughly, then set the basic mixture to obtain an average 45 percent duty cycle at idle. Sears has a VOM with a duty cycle function for about forty bucks.

www.landiss.com/mixture.htm

Also check the PCV system for clogging. Pull off the small hose from the cam cover at idle. You should feel light suction. If not, the system may be clogged forcing blowby "backwards" through the large hose that routes from the cam cover to the air cleaner cover.

Duke