Fumes in truck

Have a 94 Ranger that is fillling the cab with fumes that making me and riders sick.

1.Thought maybe a leaky heater core...but doesn't smell sweet and not low on coolant. heats ok
2. The shop says there is no leak in the exhaust system....hum.
3. Head gasket ok.


Smell is not a real strong but a couple minutes in this thing and the eyes will water, cough like a chain smoker, lips go numb and generallly nasea.

Any experiences like this out their or other ideas of the possible source?

That don't sound good at all. the symptoms sound like carbon monoxide poisoning. You might want to take a double check on the exhaust system. I'm thinking you might have a leak close to the cab area. Check the exhaust manifolds for leaks (between them and the engine block, and also where the Y-pipe bolts in).
Maybe also has something to do with the catalitic converter???
These are just a guess, but get it checked fast. If it's makin you sick you dont want to wait too long! Good luck.