Hot and Bothered

Can anyone help me with this problem.I own a 2002 Range Rover 4.0v8,which runs fine most of the time but in the hot weather it back fires and looses power after it as been stood for a while in the sun,on start up it struggles to get over 5mph then it will surge forward it gradually improves over time and then after about 10 miles it settled down.Does anyone out there have any ideas.I've tested the fuel cap OK the AFMseems to be fine the engine stopped when I removed it andsrarted when I replaced it,any imput greatly received.

Hi mate, you may get more advice if you use this section purely for introducing yourself and your green oval of choice, and then search/post in the relevant section for your motor (Range Rover)

Thank you for that advice,as I am new to this forum ,still trying to find my way around.D H-T.