Help with power loss, Overheating cat and vibration.

Hello, My 89 GP 2.8L is starting to give me problems again after a year of zero problems, I was driving up a hill trying to enter the freeway when the car suffered power loss and could't go over 40 to 45 miles and the steering wheel started vibrating, The floor got very hot and it sounded like I was ridding a motorcycle instead of a car when I parked outside my house I put reverse then "D" and the whole car started to vibrate or jump harder noticed smoke outside and a burn like smell but the engine temperature was like 150 and checked the engine but there was no smoke but the cat was red hot, next day a guy from a moffler shop told me that if the cat overheated it needed to be replaced so it was but still vibrates and the new cat overheates in like 10 minutes or less and the car has no power and uses too much gas, I took it to a diagnostic even though there are no service engine light on but they told me that the MAP Sensor was bad so I replaced it but nothing, checking the vaccum lines I found one cut just below the battery it was connected to a sphere or ball so I reconnected the line and check all the lines, but still the same. Help