240 +t sporadic idle hunting issue

Just finished my swap +T today and I'm having an issue with idle. Once it's gets to operating temperature the idle will fall off as if it's been shut down for about a second and pick back up to normal. It does this about every 15 seconds. Driving at cruise or on boost accelerating, the car runs perfectly. Any ideas? I don't get a lot of time during the week to work on it so I'm trying to get some ideas for next weekend.

The car is a 91 240 with chipable ezk and ecu with tlao chips 13c turbo
740 ic
016 amm
Stock 940 down pipe and exhaust

Checked the codes this morning and I have a 223 and 212 stored. Cleared them and they came right back on. I checked the connections on the oxygen sensor mass air meter and idle air control valve and all looks good

My idle will get wonky once and a while, cleaning the throttle body, IACV, and TPS usually helps

Not that my car idles that well

It's odd that the iac and o2 sensor are not communicating with the computer. Both codes state missing signal input. I'm using the idle air control valve from the original motor along with the oxygen sensor.