pullin my hair out

Jesus,
I don't know what's wrong with my car. Sometimes it idles fine, other times it wants to die. New IAC, cleaned my TPS, set it at .917v, cleaned my PCV and screen, cleaned the mass air meter, changed my O2 on right side, cleaned my tb. I had my mechanic check it for a vacuum leak by pumping smoke into it, no dice. He did tap on the ECA with the back of his screwdriver and it seemed to idle right, coincidence??? He thinks I need a new one. I discon the batt, and pulled out the ECA (EMC)and cleaned the connector. It ran better for a while but now it's back to the same. I can even feel it missing at speed. KOEO -11 KOER - 12, 41, 91, 33. The 33 is because the previous owner took most of the ERG and other things off several years ago. BTW it has a Cobra intake, 70mm tb, j302 heads, 19lbs, aftermarket headers, 5spd, 3:55s. Before I shell out the $280 for a new ECA, I'd like to exhaust all other possiblities. I'm beginning to hate my car, and the ol' lady's grief isn't helping!! Says I should buy something sensable. HELP!!!

The ECA I'm referring to is the "computer" on the pass. side. Man, is that a pain to get in and out!
I printed out jricker's surging idle list and followed most of it and still hasn't solved my issue. I couldn't get the salt and pepper sensors apart to clean those connections. BTW I also cleaned the contacts on dist cap, rotor, and changed plugs, fairly new ford wires. Loosing my mind...

Cobra1741,
Yea I know ideally I want .999v but I thought .917 would be close enough without elongating the holes.
I did watch the meter as I moved the throttle and it all moved smoothly, not erratic al all.
TPG, Thanks for the suggestion. Do you have an idea on how to check the impedance? Sometimes it seems to be fine, idling at a red light at 900 rpm, then all of a sudden, it starts loping at 600-700 rpm and acts like it wants to kill. Sluggish coming off the light, like it has a miss. Other times it's fine.
Frustrating. Thanks for all the input guys.

No, Should I??
You mentioned testing the impedance on the injectors, could you give me a clue as to how this is done?
What wires to test, what readings i should get ect. Thanks.
btw Sorry about jumping in & out of the forum, I'm afraid it's "catch as catch can".