Another idling problem

[ab56452001]

Hi,my Vt dual fuel has of late had a pretty average idle and getting worse. The car runs better on gas than petrol !,even on gas its not great, but theres no poping/backfiring just rough idle , funny enough it runs better when warm and if i turn a/c on even better !, ive run some injector cleaner through it and checked air filter and air flow meter for dirt,looked around for split vacum lines and al seems o'k'. I dont think its an electrical thing as i said no backfiring etc and it runs better on gas, this all said it may run a few days reasonably well,then, crap again !, anybody got any ideas ?, thanks. Al

[ab56452001]

P.S. forgot to say , car starts first time and idle is o'k', then after about 5 seconds it starts to chugg and the idle drops etc, cheers. Al