Yours should come with the normal spoiler matey, only early vr's/gti's had the deep spoiler! And no point going to vw jonnyboy yours "should" have heated mirrors...standard on a highline!
Change the blue temp sensor would be my next move and also clean the cam sensor just above the coilpack...it should be shiny metal...if its caked in sludge cleaning it will make you run better!
SO how did you check them even tho they are new.DId you replace the bolts...the front bolt is known for shearing....also could have come loose?????????????????
Standard rear is about 60 iirc gearbox is 30although think you can use mk2 diesel as its rubber not hydraulic. Im runnin a turn2 poly front mount...not solid but made a difference...no vibrations
Wood knob is standard on all manual Highlines! Wood wheel was an option as were twin headlmaps an option on all models! Electrically height adjustable were an option i think but you'll find most late ones have them!