Knock sensor

Hi all I have a 1991 G-20 305 w/ 94,000 on it. Lately it has been really doggin once it has warmed up. somtimes when im holdin the gas to the floor to get up a simple hill it will just take off like a bat out of hell for 4 or 5 seconds then it throws a check engine light. I tested the code... it came up 4 blinks then 3. I dont have a manule for the van but my buddy has a manule for his 94 chevy truck, we looked up the code and it said it was something to do with the knock sensor. has any body had a similar problem or know a solution... Thanks