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Q: Stalling at stop lights

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I was at a red light yesterday and my truck began to stall, but it didn’t shut off all the way. The rpms were jumping back and forth on the dashboard and went from 600 down to 100. The Check Gauges light came on and the engine started to rev on its own. Then the rpms went back up. So I stepped on the gas and started driving. It was OK after that and OK in park. At a stop sign or stop light it felt like it was going to quit on me. It didn't happen at every sign or light. I started to think that it might be the oil pressure. It was at 40 psi when starting cold then it goes down to around 10 – 20 when idling and stays at around 20 when driving up to 2000 – 2500 rpms. I haven't driven it over that. I changed the oil pressure switch and the truck is still doing the same thing. Do you know how I can fix this? I would really appreciate it.

Hello there, this is a common fault. The most likely cause for your 1999 Chevy C2500 to stall like this is an alternator, battery cable, MAP sensor, vacuum leak, oxygen sensor, throttle body sensor, or exhaust leak. For the engine oil, the range would depend on what engine you have and the outside temperature in your area. In most cases, the vehicle at 20 psi at idle is normal. The oil pressure should increase with engine RPM’s. A qualified technician, such as one from YourMechanic, will be able to diagnose the stalling and oil pressure issues and perform any repairs required.

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