hi everyone.i hope someone can help me with this.a friend of mine has a 88 fleetwood brougham that he says it only has 30,000 miles on it.the guy he bought it from got it from an elderly couple and was supposedly used just to and from church and to the store and back.the other guy sold it to my friend.it had sit for 2 years prior.he is wanting to trade me the caddie for a ford aerostar van that i have.he drove the car to the store so i could hear it run and drive it.well he called me and told me it had a knock that he thought it was a pushrod.when i got there and started it up there was no smoke or anything there was no knock at idle.when i revved it a little the motor knocked pretty bad.i told him i thought it was a rod knocking.is there anything else that can make the motor knock that bad besides a rod knocking?someone told me a knock sensor could make one knock like that.someone had told me since the car sit for 2 years it could possibly be something with the plugs or wires to make it knock like it was.{never heard of that}i would like to trade for this car but not if i have to put a new motor in it.it has the 5.0 engine in it.i have never heard of a knock sensor to make one knock that bad but anything is possible i guess.i hope one of you guys can give me some answers.thanks.