hesitation during acceleration

I have a 94 5.7L full size chevy blazer. My problems started with a hesitation when I would go around and over 45 mph with slight pressure on the accelerator but would quit when I gave it more gas and changed to a higher gear. Then it was worse and would hesitate all the time. I went to check the timing but it idles rough with the bypass wire disconnected and the timing right on 0 degrees. It idles fine with the wire connected. So far I have replaced the fuel pump, fuel pressure regulator, egr valve, idle control valve, distributor cap and rotor, spark plugs, and wires. When I pulled the plugs I found build up on 2,3,5,8 spark plugs from I am guessing a rich mixture. I need to replace the valve seals because I burn a lot of oil and my car smokes when it warms up. Tomorrow I am going to check the voltage on the o2 sensor. There has been no service light come on at all during any of this. It has been like this for a month now and can't figure out what it is.

Just got finished driving it and everything I have done to it so far has done nothing to help the situation. This is really getting frustrating. I read in another post about disconnecting the temperature sensor and I figure it is worth a try.

This may sound simple but I see you don't mention changing your fuel filter. Hesitation caused by lack of fuel. When mine clogged I even had a weird whistle that drove me knuts for days. Hope this helps.

Sorry, I forgot to put that in there. That was one of the first things I changed out. My new fuel injectors are arriving wednesday so I am crossing my fingers until then.