I will try and make this as short as possible. Larocca's still has, and have had my car for almost the entire summer. My problem being glowing catalytic converters.
I bought a used 306 shortblock without cam, Pro-M 75MAF, and 24# injectors from a dude in my town. Block had approx. 13,000 miles at the time. About a month later I bought his used Comp Cam that he had in the block before selling it to me. I bought a bare set of Roush 200 cylinder heads and had a machine shop assemble them to complete with all Manley parts. They ported/blended the bowls and chambers and milled them .040". They also assembled and installed the motor.
Prior to having this motor dropped in my 93 which was basically stock at the time, I put on MSD and a CAI. Keep in mind I had the stock converters on at the time. So far so good (no problems). Shortly before bringing my car to get the motor dropped in I swapped the the Hpipe for an offroad one.
I finally get the motor put in and eliminated the smog pump. My car exhaust smelled so bad that something had to be done. Timing was set at 14* and all tune up stuff was brand new. TPS voltage was good as well. So I decided to order a Mac 2 1/2" catted Hpipe. This cleaned up my smell alot but I then noticed massive amounts of heat being generated inside my car as well as underhood. I didn't know what to make of it so I left it until one night I saw my converters glowing. I knew I had a problem then. Not too long afterwards I brought my car to Larocca's to have my blower installed and I told them about the converters. They said it could be a number of things like MAF, injectors, CAI, improper A/F, ect. All of which will be eliminated when I go to the 42# injectors, Pro-M 80 MAF, eliminate the CAI, and have them tune it.
Needless to say all of that was done in February. I hardly drove the car at all but the time I did was enough to lift the heads (thus needing my head gasket replaced) and burn my clutch. After that was taken care of it brought me to about May and my glowing converters was still an issue.
At this time my EGR valve and O2 sensors were eliminated and I am tuned without needing a chip.
Please keep in mind that when I was naturally aspirated and after getting blown, the car drove fine. I decreased fuel pressure by 10# and also increased fuel pressure by 10# having no affect on my problem with the cats.
Back to Larocca's again to have them check it out. After about a month of it being there they said they have a gut feeling that my camshaft may not be installed correctly and they would like to swap it out with a "blower" grind. Before I decided to go with that expensive job I had Larocca hook the smog pump up to blow air downstream to the converters in hopes of fixing the problem. Let me tell you that only made it worse. Cats glowed faster and hotter by doing this.
Larocca's said they are about 90% sure the cam swap will fix my problem so I had them order one for me and have it installed by them. They replaced the cam along with timing chain and distributor. The cam that was already in there they said was installed "straight up" and after degreeing it saw it was in at a 105* as opposed to 108*. I called Comp Cams and asked if that would create my glowing coverter problem and they said "NO". If it were retarded too much maybe but not by being advanced and extra 3*. Needless to say, converters and now headers were glowing and I had lost 60 RWHP. They then proceeded to swap that cam with a known good cam that was smaller, which they had lying around the shop. Everything still glowing and horsepower was still down alot. They pulled my coverters off and put an offroad hpipe on an the headers were still glowing. They then did a "leak down" test and found one cylinder to be leaking a little through the intake valve and another to be leaking down from who knows where but not even nearly enough to explain the 60 RWHP loss. They tried another stock computer with no resolve. Then they install a stand alone computer. The EPEC. They got my horsepower back up to where it should be said somewhere between my stock wiring harness and EEC there is a problem and they don't know what it is. Larocca claimed they got a great tune and data logged everything and I should be all set with this EPEC ($1200). My headers were no longer glowing but now it was time to put the converters back on to see. Sure enough after putting the converters back on cats glowed again. They played with timing and bypassed my MSD and boost retard with no resolve. They through a set of stock converters on too see if it was a problem with my MAC converters, but they too got extremly hot so they assumed they were glowing as well. They also had dynoed the car with the offroad and with my MAC converters and the cats showed a 15 rwhp loss which they say was normal and not indicative of clogged converters.
So NOW they say that it is something with my motor and they don't know what it is. They lost confidence after the cam swap didn't fix my problem. I still have to pay for the cam and install anyway (approx $1000). They are leaning on it being something with my Roush 200 heads but are not positive. They are basically leaving it up to me to decide now if I want to swap my heads in hopes to fix the problem because they can't gauranty it will. THEY DON'T KNOW. WTF DO I DO???
I am already in the hole for 1G. Edelbrock heads will be approx $1100 plus installation and I don't even know if my problem will be fixed. SOMEBODY HELP ME PLEASE. THX
I don't know what the original problem was but I hope you get it figured out, or that it doesn't happen on the new short block. And you really shouldn't run the cats without the smog gear. Like someone stated before, you can run the smog crap without the cats, but not vice versa. 
