I have an 87 wrangler 4.2 automatic that I've had for a couple months now. It has 4 inch suspension lift and 2 inch body lift. Im running 35 12.50 15 Goodyear tires with Kevlar. When I first got the Jeep it ran rough but every time I checked fuel mileage I was at 15. It began to run rough and was puffing smoke so I put it in the shop and found out the carb had been filled with jb weld putty to fill a leak. I ordered a new Weber from quadratec to replace the Weber that was on there, now it runs great but im only getting 11. Any ideas of what caused it?