Dropped rpm

[Oprava]

When driving, the rpm seem to be correct. However, when I stop, e.g.,waiting for green light RPM drops once in a while to zero (motor is still running). Sometimes, it returns after a minute or so to normal (600), other times it stay at zero. Once I move the car the gage show normal rpm. However, on two occasions when I started to accelerate the engine died. I can restart the engine again and continue. This is unnerving since I never know when the engine will die. What is the problem and the fix for this? Thanks.

[taillight]

Sounds like you have an intermitent wire disconect. Hard to find but try moving the wires around with the engine running. If it dies, look there.

[Oprava]

I checked the OBD codes but nothing was there but 55. Another observation. When the AC is on the RPM stays stable like a rock never dropping to zero at idle or in neutral.

[taillight]

Check fuel pressure. You might even have to tape the fuel guage to the windschield and drive until it dies.