I am looking high and lo for information on rebuilding my 4 liter YJ engine. Primarily looking at performance engine mods, strokers from 4.2 to 4.7, cams, heads, and so forth. One of the things I have been told is as I increase cam, and air throughput, the engine will run lean. Some have said to go with a JET chip, others have said change computer(?) and F/I's. A friend (?) said there is a way to use a resistor across some lead on the pin-out for the computer to trick it into running advance and force the computer to enrich the mixture. This sounds like a dangerous technique, and is something I have not heard of. Anyone else hear of this technique? Thanks!