Yesterday driving home from work, my car had a little issue. It is usually a little sluggish going up hills, especially with the A/C on, but this was more than normal sluggishness. With the pedal to the floor the car would just not accelerate and after a second it was like the car went into neutral and the engine revved up (imagine putting the clutch in and revving up). I let off the gas and eased back on the accelerator and the car started moving and felt fine after that. I havn't had any more problems today and no faults, so I'm not sure where to go from here. The car has ~140K miles. I'm hoping maybe there is a small issue with one of the solenoids on top of the tranny, is there any way to check these? Any other input would be great, I'm thinking about changing the fluid this weekend and looked for metal flecks but that may be risky. A transmission replacement may be in the future but I think it is probably too early to tell at this point.

Thanks