Update: Over the weekend, I changed out all the fuel tubing. Started the engine right up, and same thing. At first the engine runs great, but when fuel in the tank is about 1/2 empty, the engine starts to run erratically and speeds up as if it is leaning out.
Next, I raised the tank 3/4", so that the centerline of the tank is just about 1/4" below the carb. Before the centerline of the tank was over an inch below the carb. Now the engine runs great as before, then starts the erractic performance, BUT there is less than a 1/4 tank of fuel left in the tank at that point. A 10 to 14 minute flight probably will not draw 3/4 tank of fuel, therefore I should be alright.

Now all I have to do is modify the hatch so that it will accomodate the tank 3/4" higher. That should be no problem.