Intermittently when the transmission is shifted into drive or reverse the engine shuts off?

Stalls in gear it gets under load the RPMs drop car bogs drops the needle down, it tries to catch itself then ultimately shuts off. The car has a small camshaft long tubes only did this a few times when I got it in December. It makes no sense; replaced idle control valve turned up the idle helped a little bit, still shuts off sometimes. I don’t know what else to look for next move MAP sensor if that doesn't solve it I will end up selling the car. I rebuild the engine still has issues.