The Rangers with 3.0l lost the EGR system in 2002, 4.0l and 2.3l still had them.
Your '99 computer(PCM) has fuel strategies based on EGR working so I am sure your MPG is down slightly as well as CEL being on, could also be some pinging under load.
Person doing the engine swap should have kept old engine intakes and exhaust with EGR intact, but that ship has sailed, woulda, shoulda, coulda.......
There is no real "by-pass" solution since the Computer expects feedback from the system, it opens EGR valve using EGR Modulator, then it gets feedback from DPFE sensor on pressure changes to know how far the valve opened, and it adjusts the valve based on engine RPM and load, so it needs "real time" feedback or CEL will come on, so it isn't just a matter of twisting a few wire together or adding a resistor.
I am sure someone could design a circuit to trick the Computer, but that wouldn't be me, lol.
Contact some PCM programmers see if they can change your 1999 PCM software to newer version that doesn't require EGR system.
Or add the EGR system, yes replace upper intake and exhaust manifold, get EGR Valve/tube, DPFE sensor and EGR modulator.
Wiring for all of it should be there.
Or get a 2002 Ranger 3.0l PCM and change ignition and door locks to match new PATS keys, or get a mobile locksmith in to add your current keys to new PCM.
But not sure what other pitfalls might be involved with this PCM swap as far a GEM interface and sensor parameters.
Last edited by RonD; 05-14-2015 at 10:31 AM.