Transmission

Long story short. I was able to get a 2001 C70 XC from the company for 300.00 dollars they where going to put a for sale sign on it for 500.00/B.O NEEDS TRANNY AND CAT. I got 300 I have had it for 3 days. The code I got was P0144..Thats the only code I erased it and has not come on in 24 hrs..Prombaly will come on again...What is this code and where should I start to check? The tranny ( and this might be wishfull thinking). It hits a little hard when going into Drive.. and if I take off from a stop normal acceleration and keep it above or right on 2000 rpms it will shift smoothly. Also when stopping a little fast SOMETIMES it hits hard when down shifting into second (AUTO Mode) last ly some times turning whith out stoping I can make not catch for a second.Almost like all the tranny fluid went to one side. The wqish full thinking part is How are mount suppossed to feel? The on the fire wall Engine top side and front mount bottom I can wiggle the nuts a good inch either way. Any change the mount are gone and that what the issue is. I really like this car has like every option I think? Keep in mind 90 percent of the time I can control any hitting f exempt when shifting in to drive .Unless on slight hill like I send/car rolloing a little. Any help would be great. Can't check tranny fluid in this car?