1998 Pontiac Sunfire 2.2 Auto

Hi - I have a 98 Sunfire, 240 KM and it's acting strange lately. When it's hot out, it won't start properly and sounds like it's gonna give out any minute while I'm driving it - but it keeps going. Also, it's very sluggish - it's got no pep at all. And finally, I've noticed the transmission is starting to "slip" (not sure if I'm explaining that right) and it's freaking me out. Granted, the car could be just getting old and falling apart on me, but I'm wondering if any of the 3 above things (not starting well, sluggish & transmission slipping) are all tied together. I don't drive it hard and it doesn't get driven a whole lot every day, but I do take good care of it (to the best of my knowledge). Please let me know if anyone has any ideas on this - I guess I should also mention it's my first car and I'm slowly learning what to look/listen for. Thanks so much for your time.