What plug is this?

[blackenwkn]

What is this plug and would this cause my car to idle weird?

[Tippey764]

MAP sensor

It could if you didn't have the stock one hooked up

the stock cb7 location is in the blackbox on the firewall with a vacuum hose running to the plenum. That is from a newer prelude, they were mounted right on the throttle body

[Hostile]

If your talking about the one on top of the throttle body, then it's the map sensor.