Since you didn't find anything with the smoke test I would move on to fuel pressure test. Test the Fuel pressure to make sure it is up to spec then watch the pressure after you turn off the engine and see if it drops. If that checks out then maybe do a good injector cleaning (the good kind of cleaning at the fuel rail not just the can you dump in the gas tank).

A couple other things to consider.

1) You said your buddy messed with the computer settings and it really started running rough after that. Perhaps you should look closer at what exactly was adjusted.

2) He installed new lifters on an old cam. Did he do a valve job/ adjustment also?

3) He replaced the oil pump so he had the front cover off. Did he have the timing chain off at all? If so did he get it set back at TDC correctly?

 

rotten eggs is a bad cat or a clogged cat

 

My money says an air leak past the MAF, either one of the MAF O-rings is compromised, or the air intake elbow from the MAF to the Throttle Body is letting air in.

 

This was our first thought also but he did a smoke test and found no leaks.

 

What you have is oil in your oxygen sensor plugs. Cut the plugs off of your front 02's and splice them together.

 

What? Care to elaborate?

 

Why would I cut up new o2 sensors? I want to fix the problem not bandaid it. And yes I did the smoke test. Worked great by the way and there was no leak. I held that tube shut for about 5 min and the glove stayed inflated until I unkinked my rubber hose I used for the test.

 

Unplug the passenger front o2 and look in the harness side plug. Pull the white cap out and you will notice it's soaked in oil in there. That is passing voltage from the heater circuit to the sensor circuit and flipping the ecu out. The only r3al way to fix it is to cut the plugs off and splice the wires together.

 

I will have to go back and look but I did see a site where you can buy original OEM plugs to make new plug ends... but don't know where it is... if I ever got in that situation, I may would do that first...