Originally Posted by James Cole
Well I dont think thats the problem... I believe that when you have bad fuel the Symptoms appear at high engine load and rpm... Here is the contrary the jeep feels Very slow on the low rpms almost like if the computer is neglecting torque there for some reason...
Ethanol does not have as much energy as gas, and you feel that as a loss of power mostly at low and mid range. You may be getting a lot of ethanol or fueled up at a spot that does not move much fuel. Ethanol likes to attract water which compounds the effect. There was a recent survey that showed that the oil companies are not controlling ethanol content that accurately. Discussion comes up often on those vintage vehicle forums where plastic fuel tanks are used. Ethanol in high enough concentration can soften and ruin plastic tank or tank liners.
As far as timing, the ECU senses a pre-detonation condition and pulls a lot of timing for several seconds. Poor quality or low octane fuel can cause this, which results in sluggish performance.
Lots of "smoke" could be lots of water vapor, which can be caused by moist fuel or more ethanol than the fuel should have. Its normal for the V8 to have some water vapor out the exhaust when warming up and accelerating.
Not saying that's your issue, but you can get poor or sluggish performance due to the fuel.