Deceleration

[foxy]

People I've got a poser ,After traveling at 70mph and then coasting down hill why does the engine cough splutter and almost stall ? could it be my intake manifold is leaking Cheers Foxy

 

[manaen]

You can run a vacuum test to see if the intake is leaking anywhere. Usually problems like that are centered around leaking rings or leaking valve seals. Does the engine smoke at all, and what do the plugs look like? under deceleration is when oil get sucked into the engine by the high vacuum levels around the rings or the valve seals. Check you tailpipe for oily residue.

Does the truck idle OK normally? you may want to clean the IAC and your MAF