Clean out the vent hole in the fuel filler cap before jumping to any expensive conclusions.
A clogged fuel cap atmospheric vent is the cause of many complaints like the one you described.
A good way to test is to run the machine in normal duty and at the first sign of trouble.................loosen the fuel cap.
If a clogged cap vent is the trouble, the engine will recover instantly.
Probing the vent hole from both inside and outside of cap with a stiff wire (think "straightened paperclip").
If you have compressed air blow it out good after probing.
If that does not satisfy the engine, check for spark when it dies to see if you have lost ignition.

Thanks. I will give that a try as soon as the weather allows!