This engine has 289K, yeah baby almost 300K and 10k ago I put a rebuild transmission and now the engine is misfiring Cyl6/Cyl4, running rich and white smoke in the morning wondering what to do I love my Lil tahoe

 

Welcome from Florida. With almost 300k, i would go ahead and rebuild. The troubles are starting and by fixing them one at a time, they will continue to come and give you problems. Just do it now.

 

Any one a good place to get it? (New/rebuild) also it is suitable to downgrade to a V6 ??

 

I'm a purist so if possible I would have it rebuilt if you can find a good place. I have 240K on my 1999 suburban. Maybe your's needs a major tune up only if nothing is broke internally. My rotor was showing burn spots at 124K so it and the coil and wires and the distributor cap got replaced (easy to do yourself).