Kangarooing and stalling

my micra has been a pile of problems from the start i bought her 6 months ago and dispite her faults im determind to fix her at the mo she kangaroos the rev counter bounces when this happens i know the fuel filler neck is rusted and has holes in im hoping thats the problem but i cant find the part anywhere and i refuse to pay a garage to fix the old part because the part costs £40 the garage wants £400 and im a mechanic i know a rip off when i see it i've tried scrappys but would prefer a new part tbh and tha second fault is knocking going round corners both sides at the front im not sure what to change the bearings short cv joints or longer drive shafts of both sets any answers would be appreaciated greatly