Jaguar X-Type running on LPG - finding a suitable repair

My X-Type Jag was converted before I purchased it to run on LPG. The car had 73,000 miles on it when I purchased it. It now has about 82,000 miles. I understand that it was converted to LPG by the Lloyd Ash Group on 22nd March 2012 when it had 45,425 miles on it.

It ran perfectly on LPG, changing over automatically when the engine was warm. And at £0.64 pence per litre running the Jag was an absolute joy. It required a special fluid to connect to the injectors - but getting that was no problem.

But about eight months ago it developed a fault. Whenever the engine now switches over to LPG it just stalls. I haven't bothered to have it fixed until now - lockdown etc has made this pretty pointless. But now I am thinking of making greater use of the car I was wondering if anyone in the forum could recommend an LPG engineer who could give me an estimate for fixing it. And if someone could suggest what might be the cause of the problem. I live in North West London.