Emissions failure on altered B2200

The emissions issue I have with my 1990 Mazda B2200 is high HC and CO at cruise, and high CO at idle. I replaced the blown head gasket and head checked for faults, it overheated after. Replaced the radiator and it now runs hot (between 1/2-3/4). I hollowed the cat under the truck when I got it 10 years ago, passed emission... no problem. 3 years ago I put headers on and 2-1/2 exhaust out (eliminated the primary cat at the manifold), RV cam, adjustable rocker arms, custom timing gear set, external water pump, and electric fan. Passed emissions the following year after upgrade... far better then I did previously.

Figure given are for the last run (Friday 12/21/2012):
HC Cruise -
CO Cruise -
HC Idle -
CO Idle -

CO+CO2 %
Cruise 14.48, Idle 10.37
O2 %
5.9, Idle 8.4

I need my truck back as this Chevy is 3 MPGs, rod and valve noise, transmission (3 speed) slips in 2nd, differential is howling at 40 MPH, and its not my truck.

I been looking at the idle/mixture solenoid issues others state, but would like to know if there is anyone who can identify the problem better. My final option is to drop the 13B-T in, but I don't want to have to mess with the frame just yet.

I had the same issues a couple years ago after gutting the emissions crap adding pacesetter and a weber...

I added a new cat and EGR to fix my issue. Which didn't fix it completely but in Ohio they allow for a certain % improvement to get a pass. That gave me a 30% improvement which let me pass - called a waiver. Check your Timing too, advanced or retarded timing will cause that too.

Look here where a MT member posted the following, maybe it will help you diagnose your issue.

Agreed with dan remove your egr and clean it at least.I would go as far as new plugs,wires, and cat (expensive but you need it) change your oil and filter.I would run it hard for 15-20 minutes hwy then go do the emission check.I know the cat is not cost idea good,but def helps and the muffler too.Do this simple stuff,tune up,egr,oil change,this might skate you by.