In need of help

Hey everyone, I have a 97 4x4 with a 305, my truck is lacking major power, when I floor the pedal my engine bogs down and sounds like its choking. The service engine soon light comes on once in a great while. I have had the obd ll tester hooked up to it several times, and it tells me that I have a misfire, and I have low voltage going to my o2 sensors. I have replaced rotor, cap, plugs, wires, catalytic converter, and my o2 sensors several times but I still have the same problem. If I have drivin the truck about 40+ miles and the engine warms up really good, than the truck runs almost perfect, it is very frustrating for me and I cant afford to take it to a mechanic if it is something serious, so I appreciate your input and advice you can give me.
Thanks

try new air and fuel filters

I've already changed my fuel filter. My air filter is a K&N and it is a little dirty but I've cleaned it numerous times since my truck has been running like this-for about a year now! I have also ran fuel injector cleaner through it. It just doesn't make sence to me how it runs fine once the engine is warmed up quite a bit. It is just getting frustrating, I know I could take it in to the shop but Im a cheap skate and rather fix it myself, so you guys are pretty much my last resort...

I am also running straight pipe right after the cat, but have been running that since I got the truck four years ago, and havent had any problems up until a year ago.

Try and find out if it is fuel related or spark/timing
related.... have someone spray either down the TBI unit when you open the throttle and see if that wakes it up.

heck dont listen to me I cant even spell ether! Ha Ha Ha