Bucking under no load

[mpj76]

I just had the same thing happen to mine. There are probably a few different things that could cause this, as in most cases. In my car, for the past couple of years, I noticed that every now and then when I started my car, it would cough and struggle to stay on for the first two or three seconds after start up and then surge up to 1100-1200 RPM for one second and then immediately drop to normal idle. I would keep the plugs, wires, cap and rotor new and the MAF and idle air valve clean and this problem would still occur randomly. Then one day it started to do exactly what you described. It would buck and hesitate under low load in high gear. I popped the hood and noticed a slight hissing sound. I traced the hissing sound to a very small crack in one of my vacuum hoses. After replacing the hose, all the above problems went away and the car idles smoother than it has it two years. Sometimes these kind of problems come and go. In my case the hose must have moved slightly during engine vibrations and movements and ulitimately the crack grew more permanent. In my case it was the hose going from under the upper intake manifold to the evaporative emmisions canister. Good Luck