91 Chevy Lumina, a couple of problems!!

[Farr52]

My car failed a E test (emissions) and the mechanic was barely able to narrow the reason down. He said it may be the EGR valve or Catalytic Converter. Prior to the test the Catalytic Converter had a hole in it and rather than spend $440 for a new one they were able to weld it. Then the test was done and it failed. Can one replace the EGR valve themeselves and how easy/difficult is it?
I also just had a new fuel pump put in and now about two weeks later the car has become slow to start. It will turn over, have new battery, but slow to grab and sometimes it takes a 2nd start. Now I'm wondering what is going on. The no start I had was the fuel pump. Could there be something that plugged up when they changed the fuel pump?
My 3rd problem is my temp light goes on and off. With the warmer days I have noticed that the temp seems to be going up a little more than it normally would. I have added antifreeze several times and it really is difficult to read the level on the overflow tank. Are we looking at a thermostat problem here and can I change it myself?
I just spent $900 on the fuel pump and a new power steering pump and with the mileage on the car I want to keep the costs down. I'm not a mechanic but I am able to do some of these things myself even being a woman....any advice would be appreciated.
I will say on thing my Lumina has almost 300,000 Km on it and it has been the greatest car...it owes me nothing...

[Manny_boy]

Tell us exactly which part of the test you failed, each one can point somewhere different.

High HC (Hydrocarbons) - unburnt gasoline - Cylinder misfire. Malfunctioning evaporative canister system. This can be the result of a malfunctioning catalytic converter. Catalytic converter completes the combustion process by converting unburnt gasoline into CO2 (carbon dioxide)

High CO (Cabon Monoxide) - fuel mixture to rich, or not enough air reaching your combustion chamber.

High NOx (Oxides of Nitrogen - your state may not count NOx based on the year of your car) - Malfunctioning EGR valve - you can change it yourself - but its rarely the problem. The digital EGR's can be cleaned. If your EGR was malfuctioning, you would see the Service Engine Soon light on your dash.

Because your converter had a hole in it, I'd bet the catalyst rods or pellets on the inside are shot. You mentioned that since you had the work done, your car is hard to start. Is it also sluggish now? A clogged catalytic converter would cause those symptoms. Becuase yours had a hole in it, if it is clogged you wouldn't have noticed until they welded the hole shut.

Oh yeah... $440.00 for a catalytic converter on a lum? No way. Go to your local muffler shop. (You'll get a better deal.)

[Farr52]

The part of the test it failed was "High NOx on Driving Test". the category is NO ppm....the limit is 675, mine was 1234. The rest of the reading's were ok.

I also got an estimate at a muffler shop for the Catalytic Converter and they were the same price....approx $440, so I don't know. It was the muffler place ( another one) that welded it for me. I hate like hell to put a new one on at this stage of the game and basically just to pass the test. But I guess if I want to drive it I won't have a choice.

As far as the EGR valve is concerned my engine light has never come on. Thanks for you help...