Had earlier thread about 04 lesabre stall, and everything replaced. Well , last post after coil pack was hopeful, Screw that. Is there a way to test the main computer? Should nt it show up though on a tester. Only code is cap cap loose. MAF hasnt been replaced either but yeah everything else done. Been reading hundreds , really, of posts about this buick issue online and NOONe has the answer! Everyone changes all the same things and it keeps returning. So, I am to main pc,,,so can i test it? Thanks

What sensors did u replace? Stalling is IAC often (low rpm to stall) Or TPS then MAF.
Have u done fuel pressure test or New fuel Filter in tune up?
Clean throttle body too..?? Vacuum leaks can cause problems too (related to small leak code?)

New fuel pump with sending unit was where we started, as fuel gauge never worked since getting car in Nov,2012. Stalling begain around March this yr at slow speeds, turning. Would restart. Then would just die at any speed- hiway , etc. Then started NOT restarting, Did Fuel filter, plugs and wires new in Jan 13, already done. Replaced ICM,Coil pack,CPS,ignition and starter relay.

The intake air control IAC controls the idle speed and also when it goes bad can cause stalling then starting issues. With a can of throttle body cleaner spray, I recently cleaned mine and the associated port inside was way carboned up. If it has not been replaced, then I would get a new GM IAC unit and clean with the TB spray the port before install.

Here is the port that was nasty down under..LOL.

Here is a better clean inside..

Personally I would just buy a new GM IAC to start with and then clean the port before install.
If that fixes it great..then we dont have to talk about replacing the TPS-throttle position sensor and how to install it.

yes cleaned, and changed with all other components. Just swapped out an ECm- car wont start- how do I reset it?

has to be programed with a high end scanner like a gm tech 2

usually you can give a good smack on the ecm while its running and if it stalls thats your issue.

When the car will not start the last few times, I have removed the START1 sensor, replaced it and it starts right up. I replaced all of the sensors last month so it is not bad, But why would that work every time. Still having stall/ not start proble, and not replacing any more parts - have done all of the ones everyone here has done for same issue with no success.

as art said before IAC, maf, and tps can cause it not to start. those werent on your list. really the best way to see without shotgunning parts is to watch values on a live data scanner. if you have a smart phone you can get apps pretty cheap to do this.

What exactly is a START1 sensor?
I have never heard of one of those before, I assume it is a sensor or another more commonly known name.

To be honest with you, the more you throw parts at the car, the less likely you are ever going to find out what the issue is, for example replacing the PCM with one not flashed to your VIN.
Did you ever put your original PCM back in?
If so, I advise you to test the sensors the others have suggested you test, rather than to continue to throw parts at it blindly.