Avensis Idling Problems

[starion]

hello all.

Any advice would be greatly appreciated.

I have a 2007 t3x-converted to LPG a couple of years ago and done approx 26000 miles without an issue.

A couple of months ago tick over started varying so had the LPG system serviced but was still the same.

Cleaned throttle body thoroughly and no difference.

Problem got gradually worse so had a diagnostic done but no errors- had a slight mis fire on idle and he suggested checking compressions- all were around 150 apart from No 2 that was on 120.

Did a wet test but only came up slightly- pulled the head off and with cams out poured fluid in combustion chambers and all the exhaust valves leaked through the port.

Found a exhaust valve goosed so replaced with new and ground all the valves in including inlet.

Put it all back together and pressure tested through both inlet and exhaust and no bubbles -and car drives fine apart cuts out at speed if clutch pressed (idle drops like a brick)

Car starts straight away and idles - checked cam/ crank sensor - mass air flow sensor and have just removed and checked both lambada sensors (thought there were 4) another issue is sometimes I try to start it sounds like the spark plugs are out - no compression although I know they are all above 150- when tried again engine sounds right turning over- coil packs and plugs swapped out of another vvti engine- re- checked valve timing and seems spot on - had EFI fuse out and running it on petrol till ECU resets things.

Checked for vacuum leaks - none ( tried on gas and exactly the same)

Think the issue lies with ( sounding like no compression on cranking) but this is intermittent - running out of ideas fast and any suggestions appreciated.

Paul