Subaru missing under load

I have a 1986 Subaru GL wagon. 1.8L 2bl carb. 4 speed, 4WD, 90,000 miles. During the winter months the car runs exceptionally well. In the summer when the engine is warmed up the car will miss badly under load. Push in the clutch and the engine will rev to redline. Put it in gear and release the clutch and we are lucky to see 2500 RPM.

Mechanic replaced carb. I replaced the fuel pump since the output was at the bottom of spec. Also replaced distributer since it was easy. Spark appears good and the advance is working.

A Catapiller mechanic said it sounds like the catalytic converter. Could this be the problem? Why would it only cause a problem when hot?

Ignition coil? $20 at Auto Zone. Prices may vary.

my ignition coil costed $65.00.

It very well could be a catalytic converter but highly doubtful. I have heard of catalytic converters making a car run rough but never heard of it to cause RPM’s to redline. I suppose maybe carburetors may be a little different to modern day fuel injected/computerized cars but I wouldnt immagine it being this drastic. Catalytic converters heat up to quite a high temperature and when this happens the inside components (looks much like honey comb) expand and make it harder for the exhaust fumes to exit the tailpipe. This can cause the car to “choke”. As far as the high RPM’s go, I cant really give you any advice except have your mechanic use his brains and mechanical skills to find out what else is wrong if anything.

thorough7, are you stewcanoe?
The question mark after, “Ignition coil” means that the symptoms could fit a weak ignition coil. The price of $20 puts it into the area of troubleshooting called, “change inexpensive (but, not expensive) parts when other courses of action cost too much money, or time.”