1996 Dodge Truck

Welcome to the forum, how long since a tune-up? Use a gage and check fuel pressure. Are there any trouble codes? You should be able to get some codes, by cycling the ignition switch, you turn the key, just till the dash lites come on, no further. Cycle the key, on--off, on--off, on, then the check engine lite starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

If the smoke is black, the system may running rich for some reason? I'd still use a gage and check for proper fuel pressure. Also, check that the pressure holds after the key is turned off. Some of the national brand autostores used to loan out fuel pressure gages. You can call and ask. Without a code or being able to look at live engine data, to see what the sensors are doing, it becomes hunt and peck for me. Right now, it sounds like it is rich, for some reason.