Hello I have a Phase 2 EJ22 from a 99 Legacy swapped  into my 1984 VW Vanagon. Motor has been running great but just noticed recently after driving for a bit the idle has started to stick fairly high (1600 rpm) and doesn’t drop after throttle tap. No issues on startup with idle, seems to going through it’s higher idle “search” then settles around 700 rpms. If I turn off car and start back up idle goes back to normal.

Checked to make sure I had proper slack in throttle cable. Cleaned IACV and throttle plate. No Cruise hooked up (read this as possible issue on other posts). Every so often (pretty rare) it will sorta stall immediately on crank but then starts right back up, haven’t thought much about it to this point. Only CEL code is associated with O2 sensor heater circuit (have changed sensor with OEM and seem to get signal from harness still throws code though). Motor runs great otherwise.
 

Looking for suggestions on where to check next?

Thanks in advance.

Bump?

maybe some issue with engine temp sensor or its wiring? opening/shorting with temp or something....?

Any CEL codes?

Only CEL code is an O2 heater circuit code.