I have a 2012 2.0L patriot that I recently bought from an individual owner. After purchasing the vehicle I noticed that the transmission begins to slip in the first gear whenever I drove the car for a long period of time. I assumed that the transmission fluid was low, but when I checked it the fluid was enough. I also brought it to a transmission specialist to check the transmission out but they cannot seem to find anything wrong with the transmission. I even asked them to change out the transmission fluid and the transmission filters inside it just to make sure these were not causing the problem. However, the problem still persists. It is only when I am at a complete stop when the rpm will rev up to 2500rpm (But no higher) but the car will not accelerate despite me pushing down on the pedal to its max. I also encountered some problems while I was accelerating, the rpm will rev up to 3000rpm or a little more and then bounce from 3000 to 2000 and up again repeatedly (like the engine was losing and gaining power repeatedly). Keeping in mind that driving on the interstate was fine (an indication that the other gears were working fine). It was just when the car comes to a complete stop (at a traffic light, or to get gas at a gas station after a long drive) when the transmission starts to slip. Since the transmission specialist could not find anything wrong with the transmission, I was wondering if there are other parts or components of the car that is causing this issue to pop up. I hope I find a solution quick because I need to drive to my work soon.