My truck starts fine but dies after about 2-3 min when I let off the acclerator and come to a stop. It runs a little rough when I accelerate, I've changed the plugs,wires, air filter, & distributor cap could it be the fuel filter? (305 with carburator)

Sounds like a misfire. But honestly it could be anything. If the check engine light is on that could point you in the right direction

Check your fuel system, especially your fuel filter and fuel pressure regulator.

This could be a lot of things. one of the tests that you need to run is shift it into nuetral when you are stopping and see if it still drops RPM and wants to stall. This will eliminate or conclude that it is a transmission issue. If it is still doing this then it could be a vacuum leak or fuel delivery issue.

Idle air control valve and possibly the throttle position sensor contacts are worn the both of them expand from heat and break contact but try first using carbon conductive grease on the plug contacts there could be oxidation or corrosion in them causing the problem before you start spending $$$$ you spent big money already with no result ?good luck stephen

Rough Running Engine - James on Engines #2 - Bell Performance

https://www.bellperformance.com/blog/rough-running-engine

Apr 21, 2015 - When diagnosing an engine with a rough idle, there are certain things that must be ... If the problem does not reoccur, the codes will be erased by the computer. ... when accelerating the vehicle, which causes a higher fuel demand. .... it was water in gas...added added Gas LineAntifreeze/Water Remover.

i want to give you the right answer but the only thing i think of is the mass air flow sensor.

It sounds like there is a problem with the Idle Air Control (IAC) valve. Its job is to open and let air into the manifold when the throttle is closed at idle. If it does not open, the engine dies at idle. The IAC is mounted on the throttle body. Possibly the valve is clogged or stuck, in which case it could be ok again if it is removed and cleaned. Or it is broken, and needs to be replaced. Or, there is a problem with its electrical connection, that needs to be traced. Good luck, let me know if you have any questions.

idle speed sensor maybe bad. check for codes

Check the primary and secondary resistance on your coil and resistance and gap on your spark plugs. Sounds like you have a high temp foul out.

Sounds like the fuel filter is dirty and needing to be changed. It's cheap and easy to swap out.