95 Lesabre

I have a 95 Lesabre that is having starting issues. It sometimes takes 13 tries before it starts and then sometimes runs roughly and other times purrs like a kitten. It seems to have some relation to both temperature and humidity. When it is very cold sometime the choke gets stuck on and it races. When i run it sometimes I have to wait 30 minutes before it will start again for it to cool down or whatever. I have replaced the spark plugs, spark plug wires, fuel filter. run carb cleaner through it several times. The fuel pump seems to be working OK with the checks I’ve done. I took it to a mechanic who put it on a machine and couln’t find what’s wrong. Help!!!

A carburetor on a 1995 vehicle?

Has this vehicle been modified?

What engine is in there? Plus, please give us the mileage.

The engine races, sometimes, during very cold weather? How cold? And, how fast?
I understand your analogy that the engine races like a choke being stuck as on a carbureted engine.
The idle air control valve (IAC) controls idle rpm with control signals from the engine computer (ECM). The ECM gets its information from several places, such as the MAF (Mass Air Flow) sensor, the engine coolant temperature sensor (ECT), etc.
The IAC, or the ECT could be at fault. There are test instruction for either in the repair manuals. The ECT sensor is the first suspect.
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800b1d68 testing IAC valve.
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800b1d72 testing (engine) coolant temperature sensor (ECT).

no carberator - fuel injectors - meant to say I put fuel injector cleaner in it No modification 3.8 liter engine 153000 miles thanks

Kit’s post is excellent. My first thought was the temp sensor, but reading through the other symptoms I agree with his other possibilities also,

The “machine” the shop put the car on, did it have an oscilloscope? The traces from the various sensors can be monitored, as well as other signals, and an enormous amount of information can be gleaned from them…if he has up to date skills.

Yep agree. It could also be an injector that sticks open causing a fuel pressure problem. You should do a fuel pressure test on it but when it is doing it. I think you need a little more persistent mechanic.

Installed new fuel filter and fuel pump but only get 10-12 lbs of pressure on guage. What do I check next?