got an 87 3.5 efi on petrol and lpg runs fine except idles at about 1200 rpm in neutral or park, holds in drive at about 600 rpm so if i merely adjust the idle speed on the plenum wont it cut out when i put it into drive ?? any thoughts on the subject would be good before i start messing about with it . :car:

8 cylinders can run at lower Rpms than 4 cylinders, give it a tweak to see what happens, you can always turn it back up, tick over should be about 850-900

Just check the reason why it's running high, mixture incorrect ? Air leaks in intake ? Or is it simply a case of the tick over screws are in too much