urgent help! vt v6 hesitation under load

[showbags]

Plese help. i,ve had this intermittant hesitation when accelerating for a couple of months now. i hope someone can shed some light. it's only a slight hesitation when you try to accelerate say, up a slight incline with out it kicking down a gear. now here is what i,ve done so far.
1/replaced fuel filter & cleaned tank.
2/tested fuel pump-pressure & volume good.
3/replaced fuel pressure regulator.
4/replaced spark plug & leads
5/checked for vacuum leaks-none
6/replaced IAC valve
7/replaced TPS
8/fitted reco injectors & new O2 sensors.
9/replaced air flow meter/MAF sensor
10/tried different ECU
11/replaced cam angle sensor
12/replaced crank angle sensor
13/checked & cleaned all wiring connectors
14/replaced ignition module & coils.
engine doesnt lose coolant, engine oil has no contamination & it doesnt set any fault codes. i hope someone shed some light as to what the problem is. the car has been to 3 different mechanics and they cant find anything wrong.

[stockyvrcalais]

hmmmmm ive heard a dirty throttle body can sometimes have that effect, maybe try giving that a good clean

[showbags]

done when IAC and TPS were replaced

[jip123]

Mine does the same thing but i had removed the rear muffler which i was told that it makes it lose power making it do that if you have done this put it back on and try it

[showbags]

its got pacemakers, hi-flow cats and two and a half inch exhaust, so thats not the problem.

[showbags]

all sorted. leaking ERG pipe between valve and inlet manifold

[acarmody]

Did you just get a new pipe or.....?