1992 Subaru Legacy wont drive above 5 miles an hour help

I am having alot of problems with my 1992 subaru legacy. About 2 weeks ago I drove the car home and parked it and turned it off when I did it shuttered really bad so I turned the key to start it and all power to the car was gone. Previously to that happening I just replaced the alternator in the car and just recently put on a new knock sensor. Now the main problem I am having is the car starts but will not drive hardly above 5 miles an hour and the cadillac converter on the front passenger side glows like it is going to catch fire and smokes really bad my uncle pulled the exhaust system off to check it and he sees no clogs at all and we are still having the problem. Not sure what else to check or where to go from here or to just junk it and suggestions would be appreciated.