haha, don't think your trans would last long behind a 150 shot. Your 1st gear might just be wearing out some, have you dropped the pan and looked for any shavings?
just drop the pan and see if there is anything laying in it. its not a big deal just have 4-5 qts to refill it.
5 quarts to be exact. Wouldn't hurt to put a new filter in. Adding 5 new quarts won't hurt anything because there's about 10 in the converter. I just pulled my pan last weekend to change that sensor.
Yeah, I'm not saying to rebuild it or anything major, just check to see how things are wearing. Only because you say you lack power in 1st, but have plenty after 2ed.
I forgot to mention, if no one has ever serviced the trans, it has a reuseable gasket. You might also find a plastic plug with an o ring floating in the pan. DONT PANIC!!! Ford put these in there to keep trash out during shipping.