I think the problem is pretty simple from a technical standpoint. You have simply installed too many components on your vehicle that are made to increase your mileage. This happened to me also.
For example, I installed headers that were advetised to increase fuel efficiency by 25%, a fuel saving carb that was supposed to increase mileage by 50%, a fuel efficient camshaft - 20%, high rearend gear ration 15%. It was great for a while, I no longer needed to buy gas! The problem was that I was saving so much that I had to stop every few miles and drain all the extra gas out of my crankcase where it had backed up because my fuel tank was so full!
I learned to live with it but it was a pain. Whenever I parked I had to post those "No smoking within 50 feet" signs.
