jeep 904 auto issues anyone want to take a crack at this please

Hi all. I thought I would try with everyone here before I got to digging into this real deep.

I have an 89 YJ wrangler with the 4.2 6 cyl and 904 auto, dana 30,ford rear 8.8 , and 35 inch tires... I am having an issue with the trans that I am having problems diagnosing. it is basically a stock 904 with a small shft kit and the transfer case has a slip yoke eliminator kit. other than that the drivetrain is pretty stock except for an aftermarket floor shifter....Any help would be great.
So, when you put it into drive or 2nd and drive around it is good. except that you can tell that it never uses 1st gear. when you pull up to a stop and then go, it starts off in 2nd and then goes to 3rd like normal and it also kicks down to 2nd fine. The problem is if I manually put the shifter into first, it feels like it is slightly pushing against something, it doesn't make any odd noises or anything else weird that I know of, its just that it seems that you have to use more throttle than you should and it feels again like I said that it is pushing against something or that something is holding it back or is not moving freely I 1st gear. then you put it back in drive or 2nd and it is fine again except it never uses first gear. I have driven it this way for a bit and not had any other issues but I may be putting it up for sale shortly and I'd really like to get this fixed. Again any input on helping get this diagnosed would be great.
Thanks again all.