how do you know if your car is in the early stage of a tune up.

Dear car guras the problem i'm having is minor.I hope!But anyway it's not missing or hesitating but someyimes on a take off it's not strong .It feels like something's holding back the power.But someother time's when i take off it's nice and strong like it's suppose to be with a strong swift take off leaving other car's in the dust.And added to the problem if i pull up to a store or something and cut off the car and start it back up now usually it only takes one quick turn to start but since this problem it may take two or three start's and once i get it started it sometimes cut back off then i have to pump the gas a couple of times then it starts .But i think it's a tune up problem or a fuel injection problem because i purchased the car a month ago and he may of said it was tuned up i don't remember but other than that it runs fine except the holding back take off .Please help me get to the bottom so i won't get had by a mechanic.Thank you harry Mckinzie.mocha_teddybear@comcast.net