Someone please help! I have a 2002 Mercury Sable that bucks (or misses) while going up small hills at around 35 mph. I have tried everything... I think. It started when it had about 40K miles on it and now has over 80K. The engine has always run very smooth and quiet and is very responsive. When it first happened, I replaced the one-piece coilpack and that fixed it for about three months when the problem returned. The coilpack had obvious cracks in the epoxy on the under side. Once again, I replaced the coil pack - although, I couldn't see any cracks on this one. The problem was fixed once again for about 13 months and then came back. I replaced the coilpack a third time - this time adding a heat shield underneath it to shield it from the heat coming from the exhaust manifold. That lasted for one month and the problem returned. Refusing to believe that the coil pack went out so soon, I replaced all the spark plugs and wires with new OEM MC parts. I also replaced the PCV valve, intake manifold gaskets, EGR gasket, and thoroughly cleaned the manifold/EGR pipes, throttle body and MAF sensor. I also checked the EGR functionality and it was working perfectly. After doing all of this, I took the car for a test drive and it was exactly the same - as though I hadn't done anything!!! Frustrated, I replaced the coilpack again, but the problem did not go away this time! The engine still runs smooth and quiet, does not hesitate and has plenty of power, but when I go up slight hills at about 35 mph; it bucks. At my wits end, I replaced the coilpack again - no change. Occasionally, it logs a P0301 code, but only when it bucks real bad. I have tried swapping plugs around to different locations, but no change. My wife has driven the car that way ever since. Anyone know what's causing this? I will be eternally greatful for the fix. Thanks in advance!

 

i have the same exact problem but it happens to my wife as she goes off an on ramp in a curve?

 

Mine did it mostly when it rained but last year in the winter it got real bad so I go to AutoZone and they tell me the price of a new one and I changed my mind and bought some black RTV and the problem has settled down. do you have the coil on plug motor mine is a 2000 coil on plug with 173k so far.