I just recently bought a 2005 ford ranger fx4 with the 4.0 engine with the automatic transmission. It's at 101,000 miles. When going into first and second gear, the transmission seems to be kinda jumpy and is hard shifting into the gears. Once I get up to speed, everything shifts smoothly. I checked the fluid, and everything looks fine. No leaks or anything.

Any idea what this may be? Thanks in advance.