Not going above 2k RPM

[Grant]

1.8, think everyone here knows my car.
Fitted the GTI inlet fanny mould yesterday and its been running fine. Done about 40-50 miles in it and then on the way home it doesnt want to go above 2k rpm. It reaches 2k then bounces, almost as if ive fitted a rev limiter and set it to 2k.
Also the induction cone will occasionally make a loud pop when this is happening? Any ideas?

Thanks