1995 Blazer missing badly / timing issue

I have a 1995 Chevy S-10 Blazer 4x4. About a month ago it started acting up. It would seem to miss once in a while especially while accelerating between 20 and 50 MPH. It stayed this way for about a month and then it got progressively worse to the point where one day I walked out of a store to find it would just crank without firing. It eventually started but has not run right since. The only code I was receiving was a catalyst system code. The exhaust system was falling apart so I had it replaced from the catalytic converter on back. This got rid of the code but not the problem. I had replaced the EGR valve, plugs and plug wires a few months back for another problem. This time I noticed corrosion on the coil connection to the distributor so I replaced the coil and the coil wire. I have had the ignition module tested (good) and replaced the distributor cap and rotor. I got a fuel pressure tester and it read 60lbs when I first turn the key and it bleeds down to 52-56lbs. When I can get the motor running, the fuel pressure is 56lbs at idle and 60 when I give it some gas. So, back to the spark. When it is running, it runs smooth at idle, but when I give it a little gas it starts running really rough. I can not go past about half pedal or it will die. It will also backfire through the intake occasionally. This means timing. After replacing the distributor cap and rotor, I cleared the OBD2 codes. There are, at present, no codes. No matter how bad it runs, nothing is coding. I was suspecting the camshaft or crankshaft sensors, but I thought that they should code if bad.

Can anyone help me out on this? I am at a bit of a loss as to where to go next on it. I hate to just randomly replace parts.