Knock engine sensor light on truck is hesitating/

Did they replace the knock sensor?Check the wire going to the sensor(knock).Look for a bare place hiting up against something ,grounding it out.Make sure the plug to knock sensor is good.And make sure it is making a good connection,Knock sensors also ground a part of the computer to feed back imformation.This connection is a must,the truck will not perform at all,stumble,miss,and carry on.Sometimes even backfire.If they did not replace the knock sensor,replace it with high quality sensor from NAPA,or oem from dealer.This sensor has to be made perfect,no room for inperfection.The knock sensor is easy to replace,they just screw in a hole in the block.When removing the sensors,nothing will come out such as oil or water,this is a dry threaded hole.It is a bell shaped sensor.If you don`t know which sensor is bad,purchase one.replace one,and if there is no change,replace the other side with the old sensor you just took out,it will be a good one.I hope this helps you,Let us know if it does.