1995 Ford Contour Cars' actions and description of the pro

I have a 1995 ford contour GL, it seemed to be ok when I first purchased it. Seemed as if the engine? Was reved up to high, never bothered it to be reved down. Then I noticed that the check engine light was coming on and stayed on for a while then would go of then rusume being on. I purchased the car one week ago from a private seller, one I got home my boyfriend said if would shake really bad while driving at higher speeds. Higher than 45mph. So he took it 2 a mechanic and they rotated the tires and said that I had bad tires, bought used ones and kept 1 bad one and one that was ok. Swo left one day and it kept shutting off and eventually wouldn't start. So took it to another mechanic and they said it needed rewiring. Upon looking at the stuff under hood all of the wires were very died out looking and would crumble to the touch which exsposed raw wiring and think it may be through out the car and something may be touching and that's why the car isn't performing at least decently. Please let me have your opinion on this matter so I can get it fixed. I was quoted 1300 from the ford company. Trying to get this ddone professionally, but the fee is outrageous! HELP!