1983 "L" with emissions problems

This could really be a multitude of things. But, yes, clogged exhaust can cause some bad problems. It sounds like you also have some other issues going too. I can't remember, does the 83 have a computer controlled carb and ignition or is it still Duraspark ignition? The way to tell if you are unfamiliar is the Duraspark has a vacuum advance on the distributor, whereas the computer controlled ignition has a grey module on the side of the distributor. A computer controlled carb would have a fuel control solenoid on it (red and white/red wires coming to it) and a throttle position sensor on it. If you've got a computer system, I would scan for codes, but I don't think the 83's had the computer. If not, I would start with new exhaust and a carburetor rebuild.

A clogged cat can cause it to turn red as will muffler.my olds 442 had a 4bbl quad jet and the dump valve went bad that so carb can cause it.as to emissions you need egr system working .gases need to be recircleated .as old school system it will require everything working to pass test.the guy who used to help me in N.J. Would put in it was a rotary engine and ac on high .and if that didnt work we stick the tube in a different car. That was back yrs ago good luck

I know on the early 80's cars, the Thermactor vacuum switch was located on the firewall. The relay was located behind the passenger side kick panel where the later cars had the computers mounted. None of the components are made anymore. I tried to make a rigup on my car like that, but couldn't get parts. Your only hope is a junkyard.