3 litre Patrol engine problem

Can anyone help diagnose my problem. I have a series 3, 2002 Gu 3l Patrol with 210,000 km on the clock, I have had the vehicle from new. I blocked off the EGR valve two years ago ( 70,000 kms ago) and I fitted a D Tronic chip a year ago and have done approx 35,000 km since fitted.

Whilst driving today, running lightly loaded and just entering a main road doing approx 60 kph and accelerating lightly the vehicle started shuddering and lost most of its power along with huge quantities of light to mid grey smoke coming out of the exhaust.
I checked the dash expecting to see if the engine management light was displaying, but it wasn't and didn't for the 6 or so kms that we putted home after checking oil and water levels. There was no warning light of any type but the car idled like it is running on 3 cylinders. I got 2000 rpm ok but she was so gutless that I had to run in 4wd low range, first gear, to get up a fairly steep hill on the way home and second gear low range after that (keeping two wheels in the loose dirt on the edge of the road). All the while I was putting out enough smoke to justice to a small bush fire.
I have changed the fuel filter but that has made no difference.

My next step if no one can help will be to disconnect the Dtronic chip and run the motor to see if I can get the computer to throw a code to give me some direction. Perhaps the chip is preventing the ECU from recognising the problem or perhaps the chip is the problem.

I would love to hear from anyone who has had a similar experience or thinks that they can help me out.

Cheers
Thommo(wa)