Dave,bosque wrote:Not really a conclusion because I still get a sputter when at cruise speed and let off the gas but, oh man, is it better.
That's a typical sign that you have a leak in your exhaust system. I used to go nuts with it until a friend told me about this condition in any car. A possible culprit could be the shaft of the heat control valve. In the picture it's actually #11. Over the years, wear of this shaft at the wall of the exhaust manifold produces a gap big enough to allow fresh air, that when mixed with unburned fuel, will produce this sputters.
There's no easy fix to the valve itself. In my case, since I was very annoyed by the constant sputter, I welded the shaft in place, at the opened position of the heat control valve. This heat control valve diverts during cold starts, part of the hot exhaust gases to heat the underneath of intake manifold to allow for a better combustion. Rest assured that you won't have any problems. I driven during the winters here in Virginia in 10°F (-12°C) without any problems. Our Patrols are not daily drivers any more to the point that this issue will pose some problems.
What's more, I could bet some money that half of the Patrols of our members have the bimetallic coil spring #12 inoperable, so basically the heat control valve inside is doing nothing!!
Any exhaust leaks at the gasket for the pipe will also cause this.



