1992 Buick LeSabre - wont start

I have a 1992 Buick LeSabre, 56000 miles. During cold weather it will start like a dream - during hot weather it has difficulty starting. During hot weather the engine will turn over & over, when it does catch, it will "chug" and shake like its about to stall (sometimes it does). Again, this only happens during warm weather.

It is currently sitting in a dealer's repair shop and they are scratching their heads. They have replaced the fuel filter, fuel pump. They have checked the ignition modules - OK. They replaced the spark plugs & cables. They checked the temperature sensor - OK.

I related the story of temp sensor being akin to a choke on carb. A bad temp sensor would restrict the fuel flow beacuse the sensor would think the temp was too hot. This sensor checked OK.

I had a different "national" mechanic shop replace the crank sensor.

By all accounts this car should run. Nobody can figure out why it won't start in warm weather and it will in cold (P.S. I live in Buffalo, NY).

Any help would be greatly appreciated. Dealer is starting to charge me by the hours for a guy to sit and scratch his head!

No replys yet huh.
Well I live in the Western New York area so I'll take a guess.
That's awfully low mileage for a 92.
Assuming all the basics have been ruled out by qualified
techs, let's look at the things that are not allways obvious. With that low mileage, the car is either short tripped, or wasn't driven for awhile. Since I'm already guessing, I'l assume it's been short tripped. I have seen short trip cars experience carbon build-up and fuel system varnishing. Both conditions can cause hard starting, especially on the first start of the day. The carbon build-up on the valves is porous and will absorb the fuel, causing a very lean mixture, and thus hard starting and poor running. But as the car warms up, the carbon becomes saturated with fuel and the engine smooths out. Add in some dirty fuel injectors, and the problem worstens. Cold weather may hide these conditions by richning the fuel mixture at start up, letting more fuel reach the cylinders instead of being absorbed by the carbon, letting the engine start easier.
You may want to try a fuel injector cleaning and a top engine cleaning, Along with a thottle body cleaning.
A good injector cleaning isn't cheap though. It requires the proper equipment to do a thorough job. A do it yourself at home kit won't help.
Well, that's one of my guesses. It might be something else all together. But I have seen this problem before.
I was a A.S.E. Master Tech for 25+ years, so it's an educated guess at best.
Let us know how you make out.