I had the Low Idle and no tach problem and found that it is typically the OVP relay.
I pulled out the OVP, took it apart, resoldered the internal connections, reassembled it and reinstalled.
Problem solved for about a day, then reappeared.
Went ahead and bought another OVP, 'used but tested' and this also did not solve the problem. I put in a new fuse too.
If I plug in the OVP (either one) while the engine is (barely) idling there is a very short return to normal idle, barely noticeable but still noticeable, but then the idle drops back down immediately so low that the engine shakes. I can repeat this over and over, it happens just as the connections are made to the OVP when I plug it in, but the effect is ultra short before the problem reappears.

This has me stumped, any takers?

Thanks in advance,

Dan

 

Errr...Huh?