Okay, first off, how to check it:
CHECKING OIL LEVEL
- With transmission at operating temperature, park vehicle on level surface.
- Operate engine at idle speed with parking brake applied and move selector lever through each detent position. Return selector lever to Park.
- With engine idling, remove dipstick and check fluid level. Fluid level should be between arrows on dipstick.
- Add fluid as necessary to bring fluid to proper level. Use only fluid meeting Ford Qualification No. M2C-138-CJ, Dexron II or Mercon. MERCON(R) automatic Transmission Fluid is being replaced by MERCON(R) V as a service fluid, as per TSB 06-14-4
I think you have athe AOD transmission, which means no drain plug---, so you have to drop the pan. Anyway, I think, given that you have some slippage issues , that you should invest in a fluid change and filter change at a repair shop. This way, you know you have the right fluid, in the right amount, and a clean filter, and then you'll know if you have actual transmission issues or not.
There are aftermarket suppliers on the Internet who can sell you a transmission pan with a drain plug.