Loss of power Toledo 1l TDI

Hello, about a year ago I bought a seat toledo 1l Bj.98 TDI I am very satisfied with the car but there is a problem that occurred 2 weeks ago and that the pull is simply not the funny thing anymore that no matter what weather it is hot or cold whether the engine is warm or cold the pull simply does not come at the highest speed 130Kmh and that with very big toil however this is not always so easy when speeding up e.g. in the second course the power and all of a sudden dead pants can’t explain to me that was at VW today wanted to let the error memory read out but they don’t know where the plug is. Can someone tell me what it could be, or villeicht where this plug is installed. I don’t know where to start looking. It’s a Toledo TDI 85 KW Bj 98. Thanks in advance