Brad,
sounds like a bad EGR Valve
If the EGR valve is bad, wouldn't that cause a flaky idle
all the time? Why just when he decelerates to a stop?
EGR valve is easy to check, though. Just take the hose that goes to it, apply vacuum to the hose (suck on it!) and the engine should stall. If it does, the EGR valve is okay. If it doesn't, the EGR valve is probably clogged.
But if the valve's clogged, that means there's
no EGR action -- ever. Since there shouldn't be any EGR action at idle anyway, why would
that make it stall at idle? There shouldn't be any EGR at idle to begin with.
Hmmm. Maybe the EGR
control circuits are messed up, putting vacuum on that line at idle, when they shouldn't. But, again... why only when decelerating?
Can you help me here? What am I missing?