2005 Ford Taurus check transmission light on?

I am having trouble with my 2005 Taurus transmission slipping. i was going to change oil and filter, but at 90,000 miles, that not recommended-----according to many i have asked.. I did syphon out 24 oz. of fluid, and put some of that lucas no slip in. Ive never known anything like that to work, but for 13.00$, i was praying for a miracle. There was some improvement, to my surprise, but sporadically the check transmission light comes on don't have any idea, but when this started, the brake and i guess gas cap light lights stayed on ,on the dash--------coincidence? its a nice car, I have a 2004 I totaled, but still have the running gear<aka. the motor and trans.> Will the 2004 trans fit without a hassle Thank you for you're time, Larry