When my 97 2.8 is cold it bucks a little. It also doesn't seem to have the power it should. I got 0174 and 0171 codes a few weeks ago but they haven't come back. I've swapped the maf, checked for vacuum leaks. Not sure when the fuel filter was last changed....

 

seafoam the car and check your plugs

 

I had low rpm bucking at about 30mph, it turned out to be plug wires. I vag'd it and found misfires so I swapped some wires around and the misfires followed the wires. Changed the bad wires and good to go now.

 

Its been seafoamed and the plugs are new. It doesn't feel like an ignition buck, feels more like a lean surge/buck.

The fact that it does it worse sometimes when its cold means that it does it even in open loop right? The vag-com shows a rough engine torque.

I'm not sure how to check fuel pressure, but could it be a restricted fuel filter? I don't know when it was changed last, if ever.