I have a 1.9 tdi 130 2004. It has had a 170 bhp remap. I've not had it long but I have noticed a decrease in power and throttle response, when I pull away there's a small cloud of smoke behind me. It now definitely doesn't feel like 170 bhp.
I am led to believe it is a blocked or blog EGR valve, and having researched a little it does appear so, there is also a small amount of oil deposits around the egr. I'm probably going to buy an EGR delete.
Any help would be great please