Hello everyone, I'm new the this site, I have a 1997 4.6L Cougar with transmission problems, it is stock with a cooler. It won't shift out of first at wide open throttle and it feels like it is slipping in overdrive when going uphill at around 40mph and give it a little throttle to get it to down shift into third, it will buck or jerk a few times before downshifting. It shifts fine during normal driving at light to medium throttle except for the buck/jerk sometimes on the 4-3 downshift. The PCM has no codes and I've checked all the engine sensors. Also did a transmission fluid and filter change hoping it might fix the issue, and checked the 1-2 accumulator piston and springs, all looked normal. Need some advice on what to check next. Thanks!