Rpms wont go over 5000?

Ive had a 93 ford probe for about a month now, the car was sitting for a while when i purchased it, when i first started driving it it would stall, so i clicked the fuel pump reset on in the trunk and it didnt stall any more, been driving the car two and from work every day no problems, but i just now noticed it wont go over 5k rpms when in neutral and first, havent tried any other gears, could it be because the car was sitting for so long its the fuel injectors fuel pump or fuel filter? Any help is appretiated thanks!