On higher mileage vehicles, one or more EGR orifice in the intake manifold may plug with sludge. This can cause the engine to misfire when first accelerating because too much exhaust gas is directed into the cylinders where the orifice is not plugged. Cleaning the clogged passages should correct this concern.Google+
Car Problem Reports
Mercury Monterey EGR Orifice in Intake Manifold May Plug With Sludge and Cause Misfire
Mercury Monterey Problem
Average Mileage: 100,160 mi (72,000 mi - 129,000 mi)
Visitor, 2005 Mercury Monterey, 129,000 mi
When I am slowing down or stop it shutters and stalls. When I was driving it bucked and jumped a few times.
hesitates when accelerating. problem getting worse.