I had my '83 GS out on the highway yesterday and ran well up to 85mph. Today, cudn't get over 50 MPH, kept sputtering and losing RPM even with it floored. Ran OK 1st thru 3rd gears up to 40 MPH, then...putt putt putt.... What should I check 1st?

 

Fuel filter, ignition and exhaust.

 

LOL thanx...but thats 3 things! I'm guessing it's a gas thing so I should probably start with fuel filter.