I have a 2004 acura tl with 90k on it. Earlier I was getting onto the highway and as my speed raises up, my rpm dropped. I had to use the tip-tronic in 4th gear just to get home. If I drove in D or shift down to 3rd, it wont move at all. It won't even more In reverse. There was no lights flashing or blinking on my gauges. I can get into gears fine, but the car just won't move and when I rev, it makes a loud rattle noise. Could my transmission is slipped? Please help...

 

It seems to me that if the transmission was slipping, the RPMs would rise but the car would not increase in speed. If you're getting only certain gears and not others, you probably are going to have to rebuild or replace. I hope I'm wrong. Good luck... post up as you learn new information.