2003 S-Type Judders Badly after 1 mile

[gallap01]

I have a 2003 S-Type 2.5 6 speed auto with 92k on the clock in great condition but when I drive the car it is fine for the first 1 mile then the car starts slow down and when I accelerate then is a pause then it throws me forward and then slows again making the car undriveable as it constantly throws you forward and back. I got the gearbox replaced and serviced the car and still have the same issue. Anyone got any ideas?

thanks

[BigNige]

You're in reverse.

[Simpo Two]

Wild guess - fuelling issue/coil packs?