help!!! after running smooth for about 300-400 miles on the new fuel filter, the problem has occured again! :eek: my friend told me to change my thermastat. is that the right thing to do? im really broke now and im not sure can i bring it into a shop for diagnose. plz help my ka24de

problem: engine shakes really bad, and feels lost of power by 1/3-1/2.

done: checked ignition coil, wires, replaced plugs, passed compression test, new distributor cap, resurfaced rotor, used fuel injector cleaner (no leaks)