sicsubaru

I have been having loads of problems with my 1990 Subaru Legacy. First running rough, idle was bad, using lots of fuel and no power or get and go. So far have replaced plugs, wires, O2 sensor, run seafoam through( no smoke), pcv valve, some ignition computer part. So checked for codes it through 11,13,14,15,16,,17,23,24 and 49. Also the exhaust broken has broken off due to motor mount missing that I was unaware of and engine rattling bad. Please help.