yes you need to do that
it should pull well all thru the rev range. 3.5k is when it hits max torque so will be pulling at its hardest then.
give it a decent service
oil & filter - buy from VAG
plugs - buy from VAG
fuel filter - buy from VAG
clean up the dizzy yourself, clean contacts etc
then just set it up correctly, its as simple as:-
1. start engine. When at normal operating temp (at least 80 degrees on oil temp), disconnect BLUE plug from water pipe on front of cylinder head. Rev engine PAST
3000RPM 3 TIMES. (This resets the ECU).
2. Alter the idle using the screw in the throttle body. Set it to
850/900 RPM. When happy, re-connect the blue plug.