Engine sputters at different times while driving.

Check the intake air snorkle and air filter "box" for disconnected, broken or cracked hoses.

You can also use carb/throttle body cleaner to clean the Idle Air Control (IAC) solenoid and throttle body.

Another thing to check is the PCV hose. Often these hose will get a hold in them (from age and engine heat) and cause rough idle and/or stalling. The PCV hose runs under the intake manifold down to the engine block. It is kind of hard to see and reach so do this when the engine is cool.