My '05 has just under 130,000 miles. Recently had all 4 motor mounts replaced where the mechanic fastened the air box on top of the IAC wire harness so now doesn't reach the hole. Car seems to run just fine with the sensor laying on top of the fender well. My son had new plugs and wires installed at 100K. O2 sensor looks clean so guess that also was replaced. Prior to March 2023 most of my driving was highway at 50 to 65 mph getting 32 to 34 mpg's. Had to replace the IAT and cam position sensors in January due to motor acting like it missing at times.
Now I'm living in the Neon on a temporary basis. I run the motor on occasion to warm up the interior when real cold at night and do more driving at speeds 50 mph and below. Was getting around 22 mph and now has dropped to 16 mph, with idling for short periods of time appearing to consume an usually large amount of gas. The air filter was replaced after the plugs were so is clean. I haven't looked inside the throttle body to see if it needs cleaning along with that air flow wire.

I didn't exceed 65 mph when the shot motor mounts were in use. Had the TB kit installed when replacing those so added a fuel system cleaner to a full tank of gas before taking out on the interstate to check it's high speed performance and mpg's during a 200 mile drive. The car has exceptional pickup and flew along at 70 to 80 with eased where it got 36 mpg's. The gas usage at idle always seemed high then got worse after filling up with cheap Murphy's gas. That mess also reduced it's running performance so topped up the tank when half used with a top tier brand (Shell). Since then the idle usage has steadily dropped. Still runs like a scalded dog when I mash down on the accelerator so am unsure what the the cause may be. I have my '88 Chevy G30 van parked at a self-storage place where it's ran at idle for a period of time every two weeks to charge the battery. Has a 5.7 TBI w/280K that uses less gas at idle than this 4 cylinder. Got any tips that may improve the usage at idle?