Hey, I drive a gu patrol y61 lpg and gas 4.5 has had. An issue where over a couple of months wouldn’t start sometimes just continue to crank then eventually start and go fine for a good couple of weeks then do it again now it won’t start at all nearly all the time and been at mechanics for the last three weeks
Changed
Coil
Spark plugs
Fuel pump
Cleaned tank
Checked all grounds In engine bay
NATS light does as it should
Flash when no key is in ignition
Off when key is inserted

Mechanic said he traced it to ignition area and when you tapped it it would start 99% of them time told me to come get so I could take it to auto sparky
Not it won’t start at all no matter what I touch

Any ideas