I have a 92 pontiac grand am with the 3t40 trany. I want to know how to rebuild it. I know theres haynes and atsg service manuals. Which manual has the best info on rebuilding it? Is there any special tools that I need for this also?

This reason it needs rebuilt cause after changing filter and fluid there was change in the behavior in drive. I still have to use 2nd for it to shift gears right. Its a 3 speed automatic front wheel drive with the 3.3L engine. Heres the vin if you think it doesnt have a 3t40 trany. 1G2NE54N8NM013061

The ATSG manuals are much better than Haynes for transmissions. The only real special tool you usually need is something to compress the clutches together to remove snap rings, but it can be done without the specialty tools. The best thing to do is get the manual and read it. The pictures will show the specialty tools in use, and you can determine alternate ways of dong the same thing.

Just a note, it sounds to me like you might just have some crud in the valve body causing something to stick. Before you do a complete rebuild, you may want to try pulling the valve body out of the trans and cleaning it. I would have the manual on hand for that also.