Help with Legacy issue

[Greg Davison]

I have a 2007 Legacy on 187,000 miles, had factory fit LPG system but has not worked for some years. Had LPG head fitted with hardened valves. It has started dropping a cylinder under acceleration but runs fine when not pushed and at idle. The O2 sensors showing EML. No exhaust smoke. My garage says it cannot find anything on investigation apart from high emissions and say it could be burnt valves and I should scrap the car. Would a burnt valve cause poor engine running at all times? Any suggestions?

 

Thanks

 

Greg