I have the same problem since 1 year. getting worse every months.

Smoke coming from exhaust is sign of a few things wrong. Either the petrol -air mix is not correct and rich fuel mix is going in. Worse oil seal leak. This means engine oil from sump is finding its way into engine cylinders and igniting with petrol. A sign that engine could be damaged soon. This needs to be addressed quickly - piston rings may be loose also.

Without knowing vehicle make or model it is hard to suggest anything further.

have u changed the fuel filter?

Al to b honest id replace the Solenoid and try again and hope it works ok....Sorry i cant b more positive.... iv a funny feeling it is worse.

any body bothered to read the fault codes to find out the area of the problem
has anybody bothered to check for blocked cat converters
has the engine coolant temp sensor being checked as it may be still telling the ECM that the engine is cold and the air/fuel mixture is for a cold engine so it is running too rich when hot

same thing happened to me, i do know my s 10 durango's problem was with the intake gaskets etc and the carburator, and the timing was off, i got the carb rebuilt and an overhaul put on it, its just timing issues, when you start and it high idles, tap the gas after a min of it being started and it'll slow down a lot and be normal, it high idles after being parked a while to warm up is what my mechanic told me mine was an 84, is yours carburated or fuel injected?? take it to a mechanic and get a diagnosis that would be your best bet, and about two months after mine doing the same the engine blew on me and it was three grand to fix, so i sold it, and it bley black smoke worse than a diesel, and it was gas, and you might get a hard knocking sound soon too, if you drive it really hard, is it a 2.8 L V6?? thats not a very good engine design anyhow, its the same as my s 10 if it is, any it'll probe die soon, happened to my friend the exact time that mine did and in all the same stages, but we drove like dumb teenagers, it was just last year, best of luck

This time tell technician to use a dealer part. Some cars are fickle.

it may be due to bad ignition module. if it so then main symptom is that it runs fine down the freeway
and as soon as you pull off on an exit it dies. It eventually gets
worse where it dies going down the road.

The thing costs more than $100 .

check power steering fluid in engine bay

Possible dephaser pulley or dephaser solenoid. Pricy