82 Cherokee Chief V8 - engine cuts out

[cyberblue]

Got an 1982 Cherokee Chief V8 360. It's on pertol but also runs on LPG.
For over a yaer now, the engine cuts out without warning and very intermittently. It happens on petrol as well as on LPG, which would eliminate most fuel related problems. Most of the time I can strat the engine up again straight away. But it keeps cutting out at a rate of several times a day to only once a week or so. We have replaced pretty much every wire/coil/solenoid under the bonnet - I'm starting to wonder if the actual ignition switch/lock is playing up - if so, where do I get a new/second hand ignition lock and how do I get it out of the steering wheel column???

Any inputs very much appreciated!!!

cheers

Rolf