Testing the TVS, Microswitch, and OVP on '86 300E?

[mwaller]

Dear Forumers -
I'm hoping someone will be kind enough to help with the following questions:
1) Where are the TVS and throttle Microswitch located? How do I test them?
2) Is there any direct way to test the OVP? Mine looks OK, and the fuse appears to be fine.
My car has received a large assortement of new parts, including a new EHA, O2 sensor, Plugs, Cap, Rotor, and Wires. I recently checked the upper and lower fuel chamber pressures, and verified that they are spot-on with factory specs.
The symptom I am seeing now is varying idle speed (500-1800rpm), and a rythmic miss when driving below 2000 rpm. Above 2000 rpm, the miss diappears entirely.
Any thoughts?
Mika