98 monte carlo 3.1

i really don't know much about cars...my monte is my pride and joy so i'm hoping to get some insight as to what's wrong with it before i take it in to spend a crapload of money on it. basically the past couple of weeks it's been lunging, i guess, not necessarily going up hills either. like the gas pedal is resisting the pressure from my foot. there's some definite hesitation from the engine. and while it lunges the rpm needle bounces erratically. and now today the service engine soon light is on and it shakes horribly. Any ideas? could this be a lower intake problem?

i really don't know much about cars...my monte is my pride and joy so i'm hoping to get some insight as to what's wrong with it before i take it in to spend a crapload of money on it. basically the past couple of weeks it's been lunging, i guess, not necessarily going up hills either. like the gas pedal is resisting the pressure from my foot. there's some definite hesitation from the engine. and while it lunges the rpm needle bounces erratically. and now today the service engine soon light is on and it shakes horribly. Any ideas? could this be a lower intake problem?
Welcome to AF, first you need to have the code read, second only a pro on site can accurately diagnose this type of problem, may be able to point in some direction with the code, but a shop will have to get involved here. I wouldn't waste time getting this looked at, could damage something by waiting.