Is your transmission starting out in 2nd gear? Does it have 2nd gear only. Take it on a test drive. Place the shifter in overdrive. Starting form a stop - look for the 1-2 shift at about 18mph, the 2-3 shift at about 30mph, and the 3-4 shift at about 45. Also can also try shifting manualy if you are not sure when the transmission is shifting. Please post the results of your test drive and I will try and help from there.
I am just now having the same problem in my 02 Silverado. I just did a tranny filter & fluid change, but I still have the same results. It seems to be in second gear starting out, shifting at red line if I don't let off the gas, or I can work the gas and it will shift before redline, but shifts smoothly into 3rd and then OD. I did seem to find some metallic sludge on the magnets in the pan,but I figured after driving 60k without a filter swap, thats what it led to. I've been told it is probably something electronic. I am taking it to a specialist soon. he builds torque converters and custom trannys for large off-road rigs and race cars.
hey man the first answer was not correct i have the same blazer it takes off really slow tell it gets to second gear. I talked to a mec. and he said that i would need to get a new transmission or have it replaced he said that first gear was so grinding out is that it only had like 5% bite left when it went to take off it still starts out in first, but that is why it starts off so slow. If your looking for it to be fixed spend some money and go get your transmission fixed and as soon as you do that you will have 100% SATISFACTIION i promise it makes such a diffrence what the mec. told me that if i wanted to no what my first gear would be like putt it in 4low and in reverse and punch it that is what he told me annd it is very tru.