P38 4.0 LPG - Misfire Under Load on Petrol and Gas

Forgot to say, had a compression test done and that was all fine.

Just been rooting around in the forum seen some posts about oil and causing parts to stick. Thinking back i had an oil change done about 5000 miles ago (due another soon) and from memory i don't recall the problem before this.

It was filled with 10/40 oil is this the correct stuff to use? Are there any additives i can use to thin the oil to see if it has got gunked up?

Was there any damage to the crank sensor? Any movement in the sensor housing?
Not likely but had this on mine and it was a real pain to identify.
Just something else for a checklist is the ring gear on the flywheel, with the access plate on the front of the bell housing removed crank the engine by hand and make sure all the teeth are there...only 1 set missing at TDC afaik.