I have had MANY issues with cooling system, even now. I have flushed the ENTIRE system, heater core included. I have replaced EVERYTHING in the cooling system except the heater core, which I have great heat and no water in my floor board plus its been checked at shop several times). Just had intake gaskets and valve cover gaskets replaced, plus radiator and water pump. Its a 95 4.3 4wd 2dr and now and then when I drive it my temp will go up and as soon as I turn the heater on it will drop FAST! I was told to replace the thermostat again because of the gasket job, even though i just put a new one on in Feb. I havent did it yet because..I heard the exhaust get louder over time and found the pipe is rusted and broke away from the rear of the cat. The cat itself has rusted out one big hole and another med size hole on the bottom. Of course there is rattle but I dont no if its just the pipe or not cause if I hit the cat then it will prob collapse. My blazer sometimes, more frequently lately, has a hard time starting and I end up having to press the gas pedal a couple times to keep it from dying. Once I get it going though it doesnt try and die ne more and this is generally during the first start of the day. My engine does need a tune up but it idles like crap at times and my gas cost has went up DRAMATICALLY the last few weeks. So I think its my cat that is the culprick. Am I right? Cause if I cut it off I aint putn one back on.

also the CEL has not came on, not blinked nothing. But with the other issues ive had over the last few mths, I seriously wonder if the light works period cause one would think it woulda came on at some point during the many probs ive had.

 

One way to test the CEL is when you turn the ignition on it should light up till the engines started.

 

The catalytic coverter has nothing to do with the issues you described and since it now is rusted out it would not even cause a back pressure problem. I would say a complete tune-up and fuel pump pressure test are in order.

 

UPDATE!! Lo and behold I was headin in town and it started cutn out and boggin down tryin to die, just like it would do if the fuel pump was dyin. BUT, I kept it goin just long enuf to get it under a tree (of course it was pourin) and lookd at the converter and it wasnt glowing but it wasnt far from it either. So after getn a ride, borrowin a sawzaw (nvr used one but did today) my sister and I cut it off. It was COMPLETELY blocked! When I got it back on the road, I was SHOCKED at how well it ran. Even the jerk in tranny isnt near as often nor bad and have way more power. My sister drove it too and said it aint ran this good since ive owned it. It does need a tune up, but im satisfied with how it is right now. Ill take loud over stranded ne day And proud to say, its not cut out bogged down of nothing after driving it around for well over 2 hrs or more!!! THERE IS TWO PROUD CHICKS TODAY LMAO

 

When mine got plugged it went up on fire lol even blew up my muffer... What i did was busted a hole big enough to get the coal out and bring her home...

Ah man good thing there was snow on the side of the road . Thats how we got the fire off.

 

I knew they could catch on fire if they were clogged completely and got hot enuf, so as soon as it started tryin to die on me I pulled over as quickly as I could without running ne one over lol Im just glad I have enough vehicle knowledge to know when I can push my luck and when I cant. And if it wasnt for the people and the posts on this forum I never woulda realized my lil probs could b caused or made worse by a converter.