My 99 alero GL runs great...85,000

Check the Blend Door Actuators

https://www.google.com/search?q=99+oldsmobile+alero+blend+door+actuator

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Oldsmobile Alero MAP Sensor - PartsGeek.com

www.partsgeek.com > ... > Oldsmobile MAP Sensor > Alero Parts

Oct 29, 2008 - 04 2004 Oldsmobile Alero GL MAP Sensor 3.4L V6 VIN: E Delphi · Click to Enlarge ... Vehicle, Engine. • 2002 (02) Oldsmobile Alero, 3.4L V6. 04 2004 Oldsmobile Alero MAP Sensor 2.2L 4 Cyl Standard Motor Products.

Part 1 -How to Test the MAP Sensor (GM 2.4L Quad 4)

troubleshootmyvehicle.com > GM > 2.4L

Jun 7, 2011 - GM 2.4L MAP Sensor Test with a Multimeter. ... 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002. Malibu 2.4L. 1997, 1998 ... Alero 2.4L. 1999 .

The following video shows where it is & how to do an oil change: http://www.carcarekiosk.com/video/2000_Oldsmobile_Alero_GL_3.4L_V6_Sedan_(4_Door)/oil/change_oil_and_oil_filter

GO ON LINE LOOK UP PROBLEMS WITH 99 OLDS ALERO.OLDS ALERO JUST LIKE ANY OTHER CAR YOU GOT GOOD ONES SOME COULD BE LEMONS.IF YOU BUY THE OLDS ALERO COULD BE GOOD CAR.BUT IF ENGINE HAS OVER 100000 MILES ON IT YOU ARE ON YOUR OWN BUYING A OLD CAR YOU WILL BE TAKING A CHANCE.

Could be several things or even more than one problem. First, determine if this is an ignition issue. When it won't start and the ignition is ON, does the instrument panel light up, i.e is the ignition circuit coming on? If not work to solve ignition issue, ignition switch, etc.
If the ignition comes ON but it won't start, do you hear or did you hear the electric fuel pump run for a few seconds? If not, work on fuel pump circuit. Don't assume a bad fuel pump, as the wiring is often the problem.

get car scanned from a mobile mech--a parts place has haynes repair manuals n askum for advice

It could be the battery is starting to go or it could be the altinator.. It would be advisable to have them both checked..

The problem may be your alternator.
Check the alternator 'IND' wire is properly connected.
Check the alternator is charging OK - Battery terminal voltage 14.0 - 14.5V approx when running.

Is your security light flashing when it does this? If so, it is going into anti theft mode. Do you have the correct key for the car? Not an aftermarket one either.

I would get the car in to a mechanic right away. Sounds like the converter might be plugged. This has been known to cause car fires.