So For the last 2 weeks or so I've noticed that my transmission shudders some going between 20-25 mph at 1200-1500 rpm's. only noticed this when going uphill's. It only shudders during this. I don't know what gear it is but anything about 2000 rpm's it shifts smooth and fine. I just replaced the shift solenoid about 2 months along with the filter and fluid. Just curious to know why it does the shuddering at a specific speed and rpm's. This is the original transmission at 153,000 miles. If you have any ideas on what this could be please comment! Thank you!