Here knocking sound coming from back of car. Car sputters when stopping. Also have strong fume smell coming into car.

SOURCE: fuel leak, strong gas smell inside and outside of car

when you look for a fuel leak, make sure the engine is running. the fuel lines will be pressurized and you are more likely to spot the leak. if you see fuel squirting, be careful since it under a lot of pressure. it might look like a single strand of a spider web. also, you should wear eye protection since gas in the eye would be a bad thing. needless to say, don't light a match or lighter for light to find the fuel leak. since gas is explosive, you probably should take it to a shop if you can't fix it. it could be dangerous if gas drips on a hot part. fuel vapors are explosive too.

SOURCE: what will cause a strong gas smell after turning off engine

Check the fuel cap gasket to be sure it is not torn or worn. After that check the vent hoses that run from the fuel tank to the charcole canister located somonwhere under the hood. Is the smell stronger under the hood or toward the rear of the car? If you cannot find the problem, a fuel leak is dangerous and should be attended to ASAp by somone that has the experience to repair the problem
Good Luck

SOURCE: 1979 cad fleetwood brougham knocking sound from,engine

Sometimes collapsed lifters or loose rocker arms can cause knocking sounds in an engine. However, the fact that there was a possible loss of oil pressure and that the knocking gets louder as the rpm's increase, would indicate that there is damage to a connecting rod bearing and possibly the crankshaft. If the latter is the case you are looking at a fairly substantial repair bill.