On my 199 4.0 V6, I am having a mixed fuel smell in the engine area while running and I have already changed the intake manifold gasket twice. Any advise???

Your choices are:

Leaking schrader valve (where you check the fuel pressure)
Leaking fuel injector o-rings (usually the top ones)
Cracked / leaking injector
Cracked / leaking fuel rail
Bad seal on the connector between the fuel rail and the gas line
Leaking gas line where it comes up from the fuel filter to the fuel rail
Leaking return fuel line (excess gas is returned to the tank)

O - rings, fuel rail, connectors are hard to check as they are pretty much covered up by other parts - a good flashlight and a mirror may help you see in tough places.

Sometimes, after you get the smell, you can turn the engine off so the air quits moving, and use your nose to find where the smell is strongest, or hear the gas cooking off.

But don't wait too long, I've had to put out an engine fire from a gas leak, ain't no fun.

iwould probibie say the ingector o rings

My buddy had a similar problem. While the engine was running I was looking in through the driver side wheel well. When I moved one of the gas lines around, fuel sprayed out of one of the braided lines onto the exhaust. :eek: Almost lost my eyebrows. Luckily it did not ignite. So dont think just because they are braided they wont leak.