well 3 tanks of techron concentrate each spaced with one regular tank of chevron, and then 3 complete regular tanks after that and I have an interesting development. What I have now is a markedly smooth engine noise under acceleration and a really noticably stronger pull when i gun it. The truck has never had this power before in the 2.5 years I have owned it and it did not have a particularly rough idle before I did this. I am going to run one more tank of techron because I have some and then some redline, but I thought I would report this to encourage others. I guess either the techron has done a real job on the injectors or it has cleaned up cylinder deposits enough to stop the knock sensor from backing off the timing. one question about timing is whether retarded timing prescribed by the knock sensor is learned behaviour by the ECU so that you have to reset it before it will try normal timing again. For unrelated reasons, I did fully disconnect the battery for a while midway through this experiment. If the old behaviour comes back then the injectors are coming off and that may happen anyway. I now have something to shoot for. If I can get the truck to run like this all the time I will stop looking into a turbo/supercharger .