I have a 1996 Blazer 4.3 4x4, I took it and had it scanned today to see why it is running bad. The first code was a P0753, which is a 1-2 shift solenoid, I knew my tranny was having some problems like no 1st or overdrive, could this be why? Can I just change out the solenoid or should I change the whole tranny? The next code is P0140 which is a heated oxygen sensor, and I know about that one too, I had a new y pipe installed with a motor change and one of the sensors is broken so I will be changing that out. The next code is P0305 which is a Cylinder misfire on number 5. This one is a new one on me, I have changed the plugs, wires, and cap with no change on it any ideas on what to try next?