stalling while maintaining speed
 

My truck is an 1988 Chevy 2500 series 2/wheel drive, it has a 350 5.7 liter with a throttle body carburetor. The engine idles fine, it does not stall when I am on the brake, the problem I have seems to be happening when I am in gear and feathering the gas to keep a constant speed, no problems when I am excellerating or coasting. I am stalling very often and it starts right back up, I believe it to be either a vacume line or the fuel filter, the fuel filter is located under the driver's seat on the frame rail. Transfuild and oil or clean and full. [/align][/align]I'm looking for some advice...[/align][/align]thanks![/align][/align]Sargent Scott S.[/align][/align]