I have a 2005 Ford F150 King Ranch that's developed a transmission issue and I'm hoping to find out exactly where to start.

Whats happening is that when braking its shuddering like the torque converter is engaging and disengaging. Then once stopped when I step on the accelerator the engine revs before slamming into gear. Also sometimes after backing up when going into drive same problem where it'll slam into gear. All other gears once underway shift fine. I'm just not sure if this is Torque Converter or Solenoid issue. I'm confident that I can do either repair but rather not spend money on parts I do not need.

So my question is, is there anything else I can do to help narrow down what it maybe any testing I can do?

Thanks in advance,
Jimmy