I have a 2008 accent with about 95k miles on it. I recently took it in to have the oil changed and the mechanic suggested I get a tune up and said my spark plugs needed to be changed. I didn't opt in for the tune up that day and I'm now noticing more problems with the vehicle. At first the car struggled accelerating at about 35-45 mph, but once it reached above that speed it ran fine. More recently the car has really struggled accelerating after it had come to a stop. Today I came out to start the car and it took a couple tries to get it to kick over. Once the car was on I could rev it up but when I put it in gear it struggled to get to 10mph and that's with the gas pedal pressed all the way to the ground. I let it set and came back to it about an hour ago and added transmission fluid, because it was low. The car started a little better, it wasn't shaking as hard, but it still struggles accelerating and won't push pass 30mph. When parked I can rev it all the way up, when I take my foot off the gas the car does threaten to cut off, but it only has once. I'm not sure where to start. Help anyone?!?