own 2010 mercury milan car turns off while driving, car is jumping as if it wants to take off fast, when at stop light car is shaking, when i fill my gas tank up the starter keeps running turn off on

A check engine light should be on. Have the codes read at AutoZone or Advanced Auto Parts.

Yes the engine light is on. I had a tune up about 2 months ago and pep boys fix the car and the light went out but now it is back on

i will take car to auto zone or advance auto parts. Thank you

I'm not 100% on this but recently my car acted similar to what you're describing I had the codes checked immediately my engine light was only flickering on & off. The car had almost zero power while high running rpms like 6,000 & only getting to 10mph. It was shaking horribly the power would kick in on & off too the code read it was "misfiring from the coil packs that go to the spark plugs" luckily I took it to a shop & didn't just have my boyfriend do a tune up because it was my engine computer system that was messed up in turn causing the coil packs to run non stop where they burned up. This is apparently a common problem with this car, if you only replace the packs & plugs it'll probably happen again. A costly problem to fix but I'm hoping it doesn't happen again with the new computer installed. Hope this is helpful for someone better late than never! Good luck

So what should I do when I take the car in for a tuneup? Besides having the spark plugs replaced?

The engine computer may need to be replaced. I had this misfire issue happen at 100,000 miles or so...low power and the engine is going crazy and shaking. Warranty does pay, but I was out of the mileage range for warranty. There is a known issue with the computer and getting a new version fixes the issue. It cost me $1500 though :(