so i think ive asked this question before but here is the scenario i went out on my rxt starts fine but when i squeeze the throttle it goes to around 3500 rpms for a lil bit before actually taking off like it should, then after about 7 or so mins of ridding it would die down back to 3500 then cuts off but after restarting it would do the same but sometimes it will ride fine for a longer period of time it shows no codes on the dash except one it had check engine light but then it just went away i had it put on a computer for a check-up and the guy said to change the tops sensor as a precaution so i did but the prob still exist (and these are new plugs)

any help or ideas would really be helpful