I have a 98 Chevrolet express van 3500 i got these codes PO174,PO171,PO300I have done everything possible from cleaning MAF cleaning fuel filter, and once it gets warm it starts to run rough....I have no idea what else to do thx

 

When the engine is cold , it may run a little rich, but when it warms up and computer system is now in fuel control ,it controls everything.

The computer determines fuel injection on time based on info it receives.
A vacuum leak that is not reported to the computer so it can make adjustments can cause this type problem.
In coming air is measured by the MAF sensor and fuel is adjusted accordingly. If, however , the vacuum leak is AFTER the MAF sensor the computer cannot do any correcting.. Good place to start is possible air getting into engine after MAF sensor location ,possibly a cracked vacuum hose or damaged intake tubing.