My '03 has a slight hesitation in first gear between 1500 - 2000 rpm. I have done the following;

Replaced Spark Plugs
Replaced Fuel Filter
Clean MAF Sensor
Check Spark Plug Wires, look to be good, Blazer only has 70K on it

I bought in 2010 with 56K on it and the intake gasket had already been replaced.

The hesitation is minimal but I have learned from owning 3 S series Chevys that preventive maintenance is better.

I have not check the fuel pressure, could be that fuel pumps is heading the wrong direction?

Thanks in advance for your thoughts!

*Anyone the best way to get to the a/c condenser?
I am Looking for leak! The dye I injected is only showing around the
accumulator. This could be here from my efforts to inject the dye.

 

Have you looked at the cap and rotor for signs of corrosion? A fuel pressure and leakdown test wouldn't hurt, you can rent a gauge from autozone, leave a deposit and get your money back when finished. It should be about 60 and not leakdown for 10 minutes with the key on, engine off!
An alternate method for finding a leak is to use soapy water and check for bubbles, unless you know someone with an electronic sniffer.