P38 Help

Hi all
Desperate for some assistance

My 2001 LPG Converted 4.0 HSE is giving me a big headache. When I start up the engine (on petrol) it runs like ****e...........especially when pulling away ,no power. Additionally once I reach about 3000 rpm the is no more power available above this and again the engine appears to miss (thought it could be fuel stravation). When I run it on the lpg it runs a lot better although by no means perfect.

Any ideas would be appreciated

Regards Colin P

if it was running fine and not been messed with it normally electrics start with plugs rotor arm dizzy cap and i take it the timing not been messed with. little trick is to start up late at nite and in the pitch black have a look under bonnet,check where ht leads run if theres a short it will show up like mini fire work, best to use good quailty leads, failing that check the coil out .let us know how you get on ,had this on my lpg and was combintion of them all, regards mostyn 07708989744.
if it aint broke dont fix it?

try here http://www.landyzone.co.uk/lz/f10/no-power-petrol-70356.html

Thank you both for your help, it turns out that it was the MAF in the end, which has been replaced and is running well