VAG question (LAC)

[tihol tiholov]

Sorry for LAC but since this is the most helpful and knowledgeable list
I'll ask:
1999 VW NBeetle 2.0 AEH engine, 220K km, starts cold fine, idles
smoothly for 2-3 minutes, idle gets lumpier after that. 
(LAC - my 1988 90Q NG does the same)
Main issues with the VW (the Audi is fine under throttle): 
1. Misfiring when given throttle, clearing up with throttle play
(consecutive push-releases)
2. Misfiring under load, esp. 2-2.5K RPM when moving from standstill and
accellerating in 2nd gear
3. A couple of days ago barely made it up a mountain with downshifting
and fiddling with the throttle.
This has been getting progressively worse over the last couple of
months.  DT Codes for random misfiring and cyl. 1 and 3 misfiring with
VAG-COM.  Sparkplugs are 20K or so, looked good, last night new ign.
wires.

First Suspect: vacuum leak, but was one was fixed a few months ago and
no code for it.  Propane torch test - no results, maybe needs repeating.
 Hearing test for sucktion noises - inconclusive.

Second and third suspects: Coil/ignition module (distributorless
ignition) and MAF. No codes for either.  Is there a way to measure some
values with a multimeter and find out if they are good?
Have a Bentley for the car but it's a service manual, no repair
procedures.
All ideas much appreciated.
TIA,
Tihol   
 

TT