4.0 P38 stalling when hot

Never posted before so you'll have to forgive the lack of technical detail
My pride and joy (1995, 4.0 SE) has developed an annoying fault.
The car will start and run fine when cold but when hot has a very rough idle and eventually stalls.
Do 70 miles a day and dont notice problem until come off power when exit A1 so make lots of lorry drivers very miffed when cant pull away from lights
Car will not restart straight away but will eventually spring into life after a few attempts but will then stall again unless keep above 1200rpm.
Problem only happens when engine hot and will run OK if cold.
Have a sequencial LPG system (brilliant bit of kit) but problem occurs whether on gas or petrol.
Have had codes read by a friend in the motor trade and came up with cam-shaft sensor and 'knock' sensor fault. Both cleared OK and car ran OK when collected but stalled at first junction
Car has full service history and a 4 year old engine that has done 38k (usual bore liner fault) so have no reason to suspect any of the mechanicals.
Am sure its something simple but have no local 'experts' and the nearest "Independant Land-Rover Specialist' (and I use the phrase VERY loosely)turned me away as it "Needs its codes reading mate !"
Love my Rangie and dont want to loose her or pay someone several hundred pounds to fix a simple fault.
All replies greatfully recieved
Please help.

You really need to go back to your indy and have the codes read,it will be the quickest and most cost effective way,and if no codes are logged then live data displays usually point in the right direction.You mention it has gas on it,the solution could easily be a tune up,(Adaptive reset) to get it running sweetly on petrol - then have the LPG checked and tuned.
Remember you have to trust someone - why dont you ask around on here for references of good experiences with indy's in your area ?

Have had all weekend in the garage with my laptop, RAVE CD, and a box of spanners.
Problem eventually sorted though, and heres how incase you ever experience anything similar !
There is a take off pipe from the drivers side rocker cover that supplies air to the inlet manifold at tick-over. The engine cannot get any other air at tickover as this is the only supply. This pipe had been bent under a water pipe and had eventually 'welded' itself shut. This starved the engine of air at tick-over causing it to stall.
The take-off on the rocker cover recirculates crankcase fumes. There is one on the passenger side rocker cover but this is shut-off by the butterfly valve when the throttle is closed.
These rocker cover take-offs assist fuel efficiency as well (RAVE CD said so !).
Hope this helps someone !