I have a 2015 Toyota Tacoma TRD pro with 57,000 miles ,automatic transmission.

In short, I hauled a very heavy load probably heavier than the truck was rated for. Since this incident the truck has never been the same. My gas mileage went down four to five miles per gallon. The transmission is shifting bad in all gears. the transition between gears is not as smooth as it used to be. The pedal feels hard to push down and not as responsive as it once was. While going up a hill sometimes it won't even go into overdrive it will go straight into fourth gear. I've been to two transmission mechanics and they said there's nothing wrong with the tranny.

I've been to a bunch of mechanics who told me I should change the spark plugs the catalytic converters, air filters, fuel filters pressure in the engine and still no one can figure it out.

The interesting thing is when I put the two battery terminals together and disconnect the battery from the car for 15-20 minutes, ie...(reset the computer) the truck goes back to driving perfectly. But, after driving 100 miles or so you start to feel it go back to its sluggish ways. There are no codes, and have kept the maintenance up to date.

Please help thanks...