RylAssassin

Ever since i bought my car back in May i noticed a wierd humming noise during acceleration at certain times. I own an 88 N/A. At first i thought it was comming from the exaust system untill i replaced the whole system and still noticed the noise. I hear it after 10-20 minutes of driving or unitll the car is at normal operating temp. After this point i hear it some times during light throttle then it goes away if i add more and more throttle and i always hear it in 5fh gear at low throttle. I honestly have no clue what it is but im pretty sure its comming from somewhere in the upper ports or maybe lower. Maybe like somethins stuck in there
Any ideas would be helpfull-Thanks