Running problem Astra MK4 G

Hi All, Astra bertone coupé MK4 G, 2.2 autosport. EGR valve went, replaced with genuine Pierburg. Throttle body changed as original butterfly valve was sloppy and large carbon build up. Also replaced exhaust from CAT back. When the car is run and I come to a stop the car tries to die sometimes. It will sit at 750rpm, then the revs will drop and suddenly pick back up. Just had a full service done and car is still doing it. Is this something that can be tuned out using OBD II live or is the EGR fixed to the ECU? Or could this be something else that is causing the issue?? Any advice/help would be appreciated 👍