reasons car shuts off throttle light appears only sitting at red light

What is your question?

when car is sitting still at right for two long and in drive the car shuts off, but starts right back up. the anti freeze all of sudden disappearing but no leaks. hired mechanic to purchase and install engine, end up cylinders 2 and 4 read 90 and cylinder 6 under 90. before completely installing engine had al spark plugs replaced oil filter and oil changed and add bought antifreeze for car. My car is telling me its driving to rich, can not read how much gas is needed basically getting to much gas not enough oxygen

What makes this problem better or worse?

mechanic installed 2008 engine from a sebring in my 2006 chysler 300 without my knowledge, until another certified mechanic said it was not the right engine for my car

How long has your 2006 Chrysler 300 had this problem?

April 26, 2020 after mechanic installed engine check light was still on