Needing some advice. 1977 280Z
 

Needing some advice. 1977 280Z
At times I can hit a bump and the idle will drop. I can usually slightly move the pin connector to the ECU and the idle will stabilize. I have changed all female connectors on the pin connector. I have inspected the ECU with a jeweler magnifying glass. The male pins on the ECU are straight and firm.
Yesterday the at would lose idle for less than a second while driving.
I have as well as others have ran the diagnostic tests in the FSM and the EFI Bible.
Any suggestions on where I should look now?
Any suggestions ar appreciated.
Thank You.

Had the same problem. It was the B.C.D.D. valve which is located on the bottom of the throttle body. A solenoid valve opens this port you can see when you look inside the TB.
Plugged it and problem solved. You will set the idle higher now because it will be to slow.
More about this in the 280Z electronic fuel injection manual section 2 page 38