Engine has no power. Find myself going 50 downhill and 25 uphill. shakes at 65.

Possible coil packs causing misfire. However I recommend diagnosing it so you don't waste a bunch of money on incorrect parts.

Using rubber hammer, tap catalytic converter .. IF rattling noise heard from converter, catalyst has broken up inside, that's 'more' than likely the cause for no engine power... > (Restricted exhaust.) .. Agree, testing is always the best route in any event.