My BD chipped TD5 D2 did exactly what yours is doing and it turned out to be the chip. I am on my 3rd BD chip now which is the detuned version producing less power but making the car drive a bit smoother. I'm 100% convinced this chip still gives me issues as I have tested a several occasions running a standard ecu back in the car and this always sorts the problems out. I have changed virtually every sensor on the car, removed the EGR, checked waste gate, replaced turbo pipes, fitted an EGT and boost gauge to keep an eye on what was happening etc etc and every now and again, my car just drives "flat". ECU Loom is fine, in fact the car is near new given all the work it has had done recently including head gasket, exhaust minifiold to name some of the big ones.
My advice is check all the waste gate, ecu loom, MAF, turbo pipes etc etc first then if you can, fit a factory ECU for a week or so so you can drive it and see if the problems presist.
Unfortunatly my car is a '99 so is non flashable otherwise Tombie would have been let loose on my chip a long time ago.
Best of luck, Mick

