Fuel problems w/ 91 S-10 Blazer 4.3L

[scottcd]

Hopefully someone can point me in the right direction...

My truck was running fine and then the fuel pump went out. I got it fixed and it drove good for a couple days, but I noticed a little hesitation at 1500 - 2000 rpms. I put a new fuel filter on to try to fix it and it drove great for 45 miles, then it seemed to flood and bogged down and I had to pull over. To start it back up I had to give it some gas and puttered home. I was able to get to Spee-Dee and got the fuel injectors cleaned and it did not help at all. Went to Auto-Zone and the computer said Throttle Position Sensor, Vehicle speed sensor, and oxygen sensor. I replaced the TPS and the computer came back all good. I bought the oxygen sensor but am having a difficult time getting it off. I was reading that the oxygen sensor only operates when the engine is warm, but the symptoms occur right from start-up, hot or cold. So, I am thinking I may want to try something else before letting a mechanic get the damn thing off. I was told it is not the fuel regulator because it is getting gas. I am thinking EGR valve, tune-up or catalytic converter. It was running good enough until I replaced the fuel filter, so I put the old one back on and still have the problem. It has ad a lot of smoke come out during the fuel injector cleaning and still seems to have a lot coming out when revving at 3000 rpms (catalytic converter?) Also, I believe the compressor is shot because it sqeals bad when you turn the A/C on. I do not think that is causing my fuel problem. If anyone has had anything like this happen please let me know how you fixed it. I will be trying to fing the EGR valve to clean it.