Start up idling problems

Gents (and ladies if there are any reading),

I was hoping you could shed some light on a little problem I've been having since getting my P38. It's a 4.6 with LPG fitted. When it's started from either hot or cold it idles really badly and will stall if I don't feather the throttle. I've had the stepper motor out and it doesn't looked coked up, I don't know how to check its function though. I've also changed the air filter elementr to no effect.

Once running the car runs really well on petrol or gas, it's just immidiatly after starting, even if it's already warm. It's not a massive problem but it does require me sitting still for 30 secs after starting making sure I don't stall, can be a pain in petrol statoins etc.

Any help as ever is appreciated.

Dont know if the P38 has an AFM (air flow meter) but on my classic i had trouble like this. Sounds very similar, have you checked for any holes in the air hoses etc to make sure your engine isn't getting "free" air in?

i would look for a bad connection at the air flow meter connection, where the connector pugs into the afm, or, has it an aftermarket air filter, like a K+N or something?
seems those symptoms are like it sucking in hot underbonnet air, maybe??