I was pretty much wondering when I would see the engine light pop up!

Ok, so here's the problem I'm having,

The first thing I find weird is when I'm parked in my driveway/start my 99 zr2/ I hear a weird scraping noise coming from underneath which i think it may be coming from the transfer case? But not sure? The sound comes and goes. I hear it best when I'm parked with the engine running (park or drive). I also have an issue which I think is related to where the sound is coming from. I put it in D or R let off the brake and it seems like something is stopping it from normally moving with ease without touching the gas. I have to give it gas and things are good. It also seems like the blazer doesn't go the the gears correctly (automatic) If I give it a bit of gas to speed up sometimes it seems like it skips a gear or slips a gear.....I merged from a 50 KPH road to a highway road of 110 KPH, when I took off to quickly speed up, it felt like it jumped gears all weird or something? Thats when the Check engine light came on! I disconnected my battery, hooked er up again and drove till the blazer till it did it again with the gears....light came on again!
Sorry if I never explained it good enough, knew to these problems!
Any suggestions my fellow blazer peeps?

 

How about getting that SES light code read and letting us know what it is? That might help with diagnosing.

 

You that would prob be the best thing to do!! Question for ya...can I just buy a GM code reader and do it myself or does a 99 blazer need to be taken to garage to have it done?
I was just looking under the truck and noticed that there was some leakage coming from where the inner CV joint goes in. Front diff? There seemed to be a bit of oil leakage around the tip where it goes in. Also there was some transmission fluid leaking out of that part! Sorry I'm not sure what its called! Tks for the advice!