[T3] Irregular Idle and Lurching etc....solved...

[J. Jonik]

Recently, there was back and forth about my 71 FI (with 73 engine) and difficulty finding and fixing Irregular Idling, Impossible to set idle, vacuum leaks, etc.

Advice was to just use the one thick gasket for manifolds.  Done.
- changed and set Aux Air Reg several times.
- New hose from AAR to Air Distributor.  Done.
- Changed Air Distributor to spare one (72?) that did not have vac hose from its back going to engine breather.
- New wire ends (about 4 in) for the six ground wires (3 sets of 2 ea) at top of engine near breather.
- Replaced oil cooler seals along the way.

  None of those things made a difference with the idling-lurching problem...though engine sounded great otherwise. No stalling, no backfire, no fuel smells, etc.

What solved the problem was -------->  changing the Voltage Regulator. 
 I didn't do any testing with VOM.  Doing that was just one of three things to try advised by a VW mechanic acquaintance across town.

Q.   Can a Voltage Regulator be tested outside of the car?   What MUST the readings be....in car, or (if possible) out of car?   That is...maybe some VRs in my collection are only good for recycling, or art.