I also have an engine that gives me an intermittant miss, fuel knock, popping sound. Smarty Jr. has been un-installed, ECM completed cleared, and flashed, Stock valve body put back in the trans, checked all the grounds and I can't find the issue. I even spent a bunch of money on new Bosch injectors, and it made no difference. I also experience (occasionally) a wicked jolt when the grid heater is cycling, and causes the injection timing to be off. The grid heater cycling sometime gives a far worse jolt than it ever should. I am afraid it is going to break the crank shaft. When it is cold out (right around the freezing mark) I'll be driving along then hear and feel for a duration of 1 to 2 seconds of what sounds like fuel Knock. Is my ECM must be getting dirty Voltage from a voltage regulator, or battery temp sensor or ???? I have know idea what is wrong with it. Driving over bumpy road should show a loose ground or bad electrical connection. I have had no luck with that though. The injectors do what the ECM tells them to do, so why is the ECM giving the injector a bad signal. Anyways, it is a very intermitant issue that I can reproduce at will. And of course, no codes.