Power loss

Bought the car private sale... After the car engine gets hot the car drops idle and will stall out if you don't catch it in time... Most time you have to put in neutral or park and hold in on gas pedal most times your chances of not stalling out is about 65% but even if you dump it in drive with the rpm's as high as they can be with blowing the engine (and yes I'm aware this can cause major damages) the car tries but continues to want to stall out. There's and odd odor but not to the extent of gag but the smell is noticeable but not always.. At times even as your driving let's say 55 mph there's times you have to feather the pedal in order for it to maintain speed.. At this time is almost like a the car drifts off to la la land and forgets what it's suppose to be doing...