D4D 2003 Power Loss

[toblerone69]

hello to all

some times ago i writed here about a problem with an avensis 2003 d4d:

very few hp and very slow to asnwer to the gas pedal

someone (and thanks for it) suggested to me to clean the egr, change maf & fuel/air filter

the egr was not so bad, bad after a good cleaning no change at all

the fuel filter make me happy but unlucky for few time (now sometimes the car has its hp, sometimes less then half)

a mecanichal friend, in the times gived (very thanks to his patience) to me just for a swap-test, in the order:

an egr valve (no change)

a maf (no change)

the 2 "turbo" valves (no change, and for test detaching they the power goes more down)

some time ago the engine led appears, but connecting a data cable and a diagnostic software, it is reported like a simple "Pre-heating A problem", so maybe does not matter to the real problem

at the end:

in the last 2 weeks maybe i notified that with a full fuel tank the car seems to have the full power, and if the level is really low the hp decrease:

question can be that i have some dusty in the fuel thank that randomly lower the power?

if so, any suggestion for a good access to the fuel tank for an avensis 5p not the wagon one?

thanks in advance for any help, and sorry for the bad english language

regards