MGF VVC - Poor Running

[The_Burg]

MGF 1996 vintage. Replaced the throttle body with a 52mm off a Trophy, (crashed by the wife).
Huge increase in performance, went brilliantly, for a couple of days.
Started missing a bit and rough running.
Tail pipe looked a bit black so assumed running rich. Fitted new plugs, filter and appears it was actually running weak.
Checked all connectors and fasteners, no issue spotted.
Trouble starting now and runs terrible. Did the throttle pot reset, even worse. Ticked over at 3k for a bit and settled to around 1500.

Any ideas? My guess is throttle pot. With no ODB difficult to check. Seems perfect from stone cold, so possibly temp sensor?

Which one though? How can you diagnose with no port?

Help!

[The_Burg]

Bumpety bump!

[onyx39]

no idea, but I can recommend a very good mobile mechanic www.mgroversolutions.com who has forgotten more about MGF's than most of us will ever know!

[AC Motors]

Coil packs on bulkhead just in front of the engine, def worth checking, particularly if you've running in the wet weather recently. Also more likely to break down when hot, common fault, rich running would also indicate weak spark / unburnt fuel. Good luck.