2002 Saturn SL2

Do u have any codes?Also when the car stalls and won't start is it flooding?Next time it stalls try holding ur gas pedal to the floor while trying to start it see if that helps. When it doesn't we need to see if were loosing fuel spark etc. Let me know u find.

U should go have the cat tested for excessive back pressure some exhuast shops do this for free it sounds u could have a plugged cat. Let me know what u find.

Hey u said before u had a couple of egr codes and some emission code I remember on those on the stick shifts they would blow the 10 amp emission fuse check that fuse to see if it's blown it's in the underhood fuse box. As far the cat being plugged u really can't just unclog it. Unplugging the o2 sensor won't help u ethier.U can try changing the coolant temp if u want there under 20 just make sure u get a brass tipped one. The plastic tipped temp sensors crack. The sensor is right below the upper radiator screwed into the head it has two wires going to it a yellow one and a black one. Just make sure the engine is cold and u will lose some coolant. Another thing u can try to see if u have a plugged exhaust is to drop the down pipe off the exhaust manifold u would take off the three nuts off the manifold and the two bolts that hold the pipe up and let the pipe drop down away from the manifold then start the car and go drive it and see if it runs better. It will be very loud but I have down it tons of times to check for plugged exhaust just don't go for a long way just long enough to see how it runs.U might want to try the temp sensor first that's the best advice I can tell u right now. Let me know what happens.

So I take it u didn't have the back pressure tested on the exhaust to see if there was two much pressure like I said before u replaced the cat?The front cat that's on the manifold could be plugged they come apart and clog up the down pipe u can pull the down pipe down and check that it's pretty easy to see when that happens.U could also check ur fuel pressure u should have like 40-50 psi to run good.U can check the coolant temp sensor like I told u before that controls the fuel going in ur engine based on the temp of ur engine when they go bad it cause ur engine to run bad or not at all there under 20. That noise u hear under the back if ur car where is it comming from?Ur exhaust fuel tank?Let me know what u find.

The coolant temp sensor is screwed into the head right below where the upper hose goes onto the head. To remove the wire u just squeese the connector. Also inspect the connector if it's corroded it has to be cleaned or replaced. If u replace th connector make sure u get a brassed tipped one the plastic ones crack. Also make sure th engine is cold when u remove it u will loose coolant.U have a stick so u probably have a ore cat in the manifold look at ur manifold if u have one it will be a square casing below where all the exhaust runners come out. It's a pretty good size if u have one see if it came apart and is clogging something up. It will be a honey comb looking thing in there. Do u still have the engine light on if u do then what codes are u getting?

The map sensor is what tells the computer how much load is on the engine by how much vaccuum it reads and turns it into a voltage reading so it decide transmission shifting fuel delivery etc. Sounds like u found the pre cat just drop that down pipe and see if there is a honey comb in there. Also make sure the coolant temp sensor connector isn't corroded. Let me know what u find.

Sounds like were getting some where I have seen pcvs do some strange things did u change it?Are u running it without the pcv?When u dropped the down pipe was there a honey comb up in the manifold?Have u ever had the fuel pressure tested while u were having the problem with the car going?I just had a 98 sl2 have a bad fuel pump similar problem fuel pressure would drop when warm.I dont think taking the battery cables off would help. Has the back pressure ever been tested when ur car has had its running problems?Let me know.