it may not be a separate issue if the B5 chassis is anything like the A3 volkswagens... there's this "K-line" to the radio that causes a whole other mess of electrical problems when an aftermarket radio is installed (both the Golf and Jetta)
Find a local with a VAG-COM . it could be more specific than a simple generic code reader (which by no means is shabby itself)
www.ohiovw.com forums
or
vwvortex columbus ohio forum
in any event, a good VAG mechanic in Cbus is ZB Lorenc, sigmatec automotive in Hilliard. He's the 1st and 2nd guy I would take any vw to
In any event, a bad pump relay, i m not sure how it would throw off the injectors timing but replace the relay, or swap it (if it fits) with another known good relay then clear the codes at autozone and see what comes back
good luck