Conversation Between subford and chris herman

Sounds like the shaking might be a loose plug wire or two.
Have no idea on the hiss or not free wheeling going down hill other than maybe engine braking.
What transmission do you have?

subford
hello you helped me a while back with my 89 e350 tioga e350 thanks a lot . I just came back from a 700 mile trip it started out where I had to give it gas to go downhill was holding back than it started making loud hissing like noise than it stopped and free wheeled freely . than got where couldn't run fast had pull over get a tow. tranny not slipping engine shakes when in gear but not in park . cat has been gutted trans fluid don't smell burnt. engine revs up like it should in park also new plugs wires dist cap and fuel filter.
thanks hope u can help