Is it a Transmission, driveshaft, or fuel pump proble?

What is your question?

I have a 98 Chevy S-10 Blazer LS 4WD 4.3L V6. It started about a month and a half ago, acting just very sluggish. I thought (I am a female, that doesnt know to much about cars) that it may need spark plugs, since I had just bought it about 2 months prior, and no telling when they had been changed. So put in new spark plugs, didnt really change anything. It just got worse as days went on. Suddenly, the check engine light came on. Had the code ran, it said I needed a mass air flow. So I replaced that. Didnt help, but did make the check engine light go off. It continued to get worse, shifting really hard, and late, not wanting to climb hills, but flying down them, very hard, no matter how hard i pressed the gas to get up to speed, when holding the speed at about 50-55 (once I could finally get it up to that speed) it would kind of stutter, or bounce back and forth. meaning the RPM's would bounce from 3000 to 2000 rapidly. I could let out of the gas a tad, and it would stop bouncing like that, but still be very hard to get back up to speed. I bought some of that stuff that you put in your transmission that is suppose to "stop hard shifting, overheating, and slipping". That didnt help either. Yesterday, while driving it home from work, once I came to a stop, and tried to take off from a stop sign, it wouldnt go over 30mph. I figured it was going to snatch into gear as it had been doing at every take off, but never did the rest of the way home, and the check engine light popped back on. I have heard all kinds of stories from people, saying its my transmission (which is most logical to me), others say it may not be getting fuel so its possible it could be my fuel pump, then some even say driveshaft or something to do with driveshaft. Can anybody pleasseee help!! its my daily driver!