Power and starting problems

[mitko]

Hi guys
There is even bigger problem whit my late 1996 new shape BMW 525 tds .
When is cold in the morning starts OK it runs OK****but wen it gets hot some times i cant even start it , it takes about 2-3 minutes, and no power at all it feels like I'm driving a 0.25cc not 2.5 liter monster .
I took it to BMW five times and all they did is took my money and told me that they don't know what it is , be cause wen they put it on the computer it doesn't show any think**. i did change the fuel and air filter but steel the same .
Please help any sugestions ar welcom
Thanks in advance