My 91 Jimmy is getting horrible mileage (11 miles per gallon) -- vehicle starts and runs just fine. I've changed plugs, spark wires, pickup coil, ignition control module. At idle speed, the throttle body injectors spray pattern looks OK (maybe the pattern is a little bit coarse). Other than poor mileage, the only thing that appears out of normal is the engine temperature -- whenever slowing down or coming to a stop, the engine temperature drops down considerably (is this maybe due to excess fuel cooling the engine?). I'm stuck -- any ideas would be appreciated