I couldn't find your original post, but there are a few other 'tibdits' that can cause smoking - maybe you already know about these, maybe not

cracked brake booster diaphragm (the smoke is usually blue-ish, and accompanied by a loud droning noise)

broken/loose ball pin in the pre-chamber - common on engines that have backfired, or had injection pump /timing problems. Smokle is normally gray-ish, and is sometimes, but not always, accompanied by a pinging sound, almost like a detonation problem on a gas engine.

algae buildup if the vehicle has sat for any length of time - changing the filters wont fix it if there's algae in one or more of the injectors.(I've just had this problem on a rebuilt junkyard 240 - 3 of 4 injectors were fouled.)

bad hoses - if the soft return lines have a leak, there might be air in the fuel, or if the vacuum line from throttle plate to the IP has a leak, it'll have the same effect as a cacked IP diaphragm.(oh - and check that the vent cap is venting- if its sealed, the diaphragm in the IP wont function properly, either)

Ciao
G