i have a problem with my 93 xj exhaust glowing red. with the stock 4.0l. then i stroked it to 4.6 my 95 doesnot have this problem i used a master tech scan tool all peramiters are in spec, same as my 95. i have zero back pressure. no cat and a spin tech muffler. the only thing that is the same is the wireing loom. it also has a new computer, o2 sensor. every thing on the motor is new. i even took it to a specialist and they didnt even know where to start. can anyone please help!!!!!!!!!!!!!!