Small Engines (Lawn Mowers, etc.): Briggs & Stratton Vanguard wont run?, briggs stratton, dip stick

Question
I have a B&S vanguard 16hp 303447 1188-E1 99120611. It developed a problem. It started fine and went out to work.  Revs started to decay as it warmed up & finally stopped.  I towed it back to the garage, checked the plugs, all fine, Started the machine and it ran fine for about 5 minutes then wouldn't rev & died.  This morning I tried to start it & couldn't.  I cleaned out the carburetor, all clean, replaced the in line filter, tried to start & couldn't.  I removed the flywheel cover & checked the leads to the coils (with the diodes in).  They showed continuity in one direction only, as I would expect.  I am now at a bit of a loss.  How can I check the coils?
Why do B & S specify oil quantity of 1.7 ltrs when my one is up to the full mark on the dip stick with only 1 ltr in it?
I look forward to your response. Thanks in advance.

Answer
 Hello Lian:

 1- If the Plugs are Firing the Coils are Good. 2- Check the Valve Lash(clearance between the Valve Stem and the Tappet/Rocker Arm). If the Valve Lash is too Close it will Cause the Engine to Do as you Described. The more the Engine Heats Up the Closer the Clearance Gets and the Valves Cant Close Properly and the Engine Slowly Loses Power and Quits Due to Compression Loss by the Valves. 3- Can you run the Engine with Starter Fluid for 25 to 30 Seconds? If Yes, then the Carburator is the Problem for the Engine Not Starting. On some of these Engines the Carburator Must be Primed to the Pump on the Carburator before the Pump will Start Pumping Gas. 4- Check the Gas Cap and Ensure it is Venting the Tank Properly. 5- The Dip Stick May be Marked Wrong. Are you Checking the Oil with the Stick Screwed into the Oil Tube? If so, then Check the Oil with the Dip Stick Not Screwed into the Oil Tube. The Oil Filter Holds 1/2qt of Oil. I have seen Several Motors with Dip Sticks Marked Incorrectly. It Seldom Happens, but it does Happen. Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John