96 LS400 rough idling, white smoke sputtering, gasoline smell

[vissine]

I got a dead battery last few weeks. When I jump to start it again, I notice it's idling roughly, white smoke comes out and later smoke gets thicker. I also smell gasoline. Scan tool does not show any code. Would it be ECM issue? The reason I think about ECM because it does not report any code although it is not drivable. Should I try spark plugs, spark plug cables, ignition coils, igniters, injectors ... first? Thanks!

[vissine]

After rough idling for awhile, the rpm became stable. I went to an auto parts store I bought a bottle of Heet water remover. I drove for about 10 minutes then stopped on the side of the road because white smoke was so thick. I left it alone for a few hours on the road then started to drive it home. Interestingly, the smoke was so much less and unnoticeable. Anyway, I only replaced the air filter and poured Heet product into fuel tank. I don't know what actually solve the problem, but I don't care any more. I guess it was something to do with bad fuel.

[Q man]

I have a 96 LS400, I I recently put in a motor however when I went to start it I noticed gas at the top of my engine and white smoke coming out can you please help me should I replace a fuel injectors please let me know help me help me help me help.

[paulo57509]

Determine where the fuel leak is and repair.

White smoke is coming out from where?  Tailpipe?  White smoke is an indication of moisture/water.  White "smoke" is typically normal at start-up after the engine sits overnight.  It's more moisture (steam) than smoke and usually disappears after a few minutes.  If it's really heavy and persists, you probably have coolant getting into the combustion chambers - headgasket?

What condition is the engine you installed?  Wrecking yard - Used?  Rebuilt?