124 trans acting up

[land sea air]

well i was in virginia today and my 87' 300E auto did somthing its never done before... going along at highway speeds the car would act like it had gone into neutral and would rev freely. i put some fluid in and it seemed to help until i was on my way back and it acted like it had been forced into third and wouldnt go back into fourth severly limiting my ability to stay on the highway. by the time i got to a safe place to leave the car it acted as if it had been forced into second and adding more fluid didnt seem to help. i had a lot of trouble trying to read the dipstick because it seemed smeared all along the stick. i know the front main seal leaks a little but i have been keeping up with it easily. since there were no noises or the associated smoke, im pretty sure that im not loosing fluid fast enough to cause these problems plus i couldnt see any visible leaks with the car idling. my mechanic friend thinks the pickup fliter in the pan is clogged and it makes sense to me but i wanted to get other opinions and options before i start ordering parts. i guess this means no more bragging about how my car doesnt leave me stranded like some of the newer cars ive dealt with