99 surge problem

i have a 99 grand am, i know a little bit about cars not much so please keep simple for me. When i am in park when car firsts starts up i can feel like the engine pushing a little bit like it wants to go, the rpms go from 1 to about 1.5 which usually when sitting normally stay at about 1 or so. Any help on what this surge going through the engine is would be greatly appreciated.

Also at times when i say come out from a store or pumpin gas when my car has sat for only a few minutes, when i start it, it stalls out after the car had just run fine for how ever long i was driving it. Please help

Welcome to AF!

It would help to know what sixe motor .

It Could be a few things causing the surging.
A vacum leak on the intake manifold, bad fuel pump.

Also the Idle air control could be the culprit.
ITs what regulates idle and when its cold is when you notice its not working properly.

It can be cleaned with throtle body cleaner.