Hi there, I am a mechanic and i have a g35 in Canada with some problems.
I have spent many hours searching threads but havn't found anything that matches what this car is doing.

first of all, the idle. the vehicle has such a terrible idle that it sounds like it has a knocking big end. but it does not as you will read further on.
The engine shakes violently but consistently and only idles at about 4-550 rpm, very low. when i try to lift the rpm the motor dies. it smells of un burnt fuel an i can actually see the fuel vapour coming out the tail pipes.

now the weird part, if i hold the starter on, it will idle with the speed of the starter, but then i give it some gas, and it revvs up like normal. no misfire no knocking noises. i know its not good for the starter but for diagnosis sake i have done it a few times.

MAF and crank sensor signals are normal, there is some oil in the spark plug tubes but im not convinced its that as while i have the key in start position it revvs up with no misfire at all.

has anybody had problems with the IPDM? does the vehicle have a set fuel map or base running map mode for cranking? this is a strange problem, the vehicle had a remote starter in it. but i removed it. i have also removed the IPDM for inspection, some slight corrosion but nothing that jumped out as obvious. the vehicle had been using alot of fuel prior to this problem which happened overnight.

any feedback would be awesome, cheers.
Jon