I have a 1999 Malibu with 2.4 liter engine. For the better part of 8 weeks or so I have been fighting a very strange stalling issue with the car. It seems I can use the car early in the morning for a 35 minute drive with no problems but 9 hours later when I drive 35 minutes home the car will just die while driving and I must stress I've never had even one problem in the morning. I have replaced the TPS because of an earlier problem as well as the crankshaft position sensor. I have installed new ignition switch, new spark plugs, new fuel filter and swapped out the ignition module and coils as I had a spare set. I've only had 2 stalling issues in the last week, the first one I was driving and the car had just down shifted and I knew the engine was going to cut out as I had no reponse as I floored the gas pedal even though the rpm'* climbed to around 4000 it was like the engine had shut off but after several seconds it came back and I continued to drive. 5 days later it just died as I came to a stop sign. The check engine light is not on and there are no codes and the car runs great except for those stalling issues. I really need help on this one as I'm out of ideas.

You certainly have replaced everything I would normally associate with this problem. Have you checked fuel pressure yet. Your fuel pump may be starting to fail.

Check all vacuum hoses for leaks.

I appreciate the info. I'm just so confused why he never has any problems in the morning. It'* like it makes no sense regarding a problem in any area like fuel, electrical or anything else because everything is happening later in the day. Here'* a perfect example, backing up 6 or 8 weeks the car was as always driving fine in the morning even if it was 65 or 70 degrees but 2 weeks ago it was cold here and tempatures never got out of the 40'* for the day but yet the car still died 5 minutes into the drive home. I'm sure I'd be pulling out my hair bit I don't have any.

Dave, when u mention of it stalling - i wonder how exactly does it. in other words, does it just gets shut of as if a key is turned of, does it shake hesitate. And when it stalls, does it start back up and after what period of a time?

When it stalls it just quits with no warning. It'* not like it'* running bad or sputtering or anything like that. I can be driving on the highway going 60 miles an hour and the car will just quit. There have been a couple times where the car has quit on me as I came to a stop sign, the car usually starts right back up and away I go. There have been just a few times where it took me a minute or so to get it started but I've never had to let the car sit for any extended period of time to get it to start back up. I also forgot to mention when listing parts that I've replaced, I've also replaced the fuel pressure regulator.

Dave, the reason i asked about it is because i wanted to imagine how it looks. For example if a car shuts off as if the keys turned off, then it most likely to be electrical, if it sputters and all that, most likely some wrong w/it drive ability vise. regardless though it is a very confusing situation that u have. basically u said driving in morning 35min its ok but back home it stalls? hmm cant think of anything but if i come up wsomething ill chip in

personally i would be hook up the scanner and look at live data when it stalls, much easier than guessing. i use torque pro($5) for android phone and cheap obd2 to bluetooth adapter 20-30 and it shows alot. other than that ive had a issue with the maf that would shut down the car. but if you had the scanner you would see that. you could unplug it when you know it would normally do it but they dont run good in open loop sometimes but might help narrow it down

Dave, the symptoms you describe sound like a bad crank shaft position sensor, but you already changed that. I wonder if you got a bad one.

I had a scanner hooked up to it and when it dies it shows nothing. I'm thinking of installing the old sensor to see if it dies will there be a check engine light and a code like there was that prompted me to replace sensor to begin with. If the new sensor is bad would I get a code or not?

No. A bad CPS sensor will not throw a code.