2002 Mercury Cougar Problem's.. Please Help

ok i have a 2002 Mercury Cougar and i just put new spark plug's and spark plug wire's in it about a month ago, and now it is still having problem's, ill be going down the road with about three quarter's of throttle and it will rev. up to about 6000 rpm's and wont shift unless i get off the gas... from looking at some other post i think it might be a coil pack but im not sure, i dont really know alot about car's so i need all the help i can get... i also went to autozone and they told me my car was misfireing, i dont remember the code they gave but they told me to come home and make sure all my spark plug wire's where pushed all the way in, and also disconnect my battery and re-connect, cuz i also have a check engine light, soooo i did all of that then took it for a ride and see if the problem stoped, and it still did it... PLEASE i need this problem fixed ASAP cuz im a daily driver, and i need this fixed... i hope to find a answer soon, thank's

First make sure you put the wires on the correct plugs. Then use an ohm meter and ohm each wire a lot of times the metal tip on the plug wire comes off if you have a crimping tool you can fix this otherwise buy a new plug wire.
Then have Auto Zone scan your engine free and post the codes. A T-P sensor will make the rpm's go up and down but give us the code.