I drive a solara 2000 I4, ever since i had issues with my fuel pump while on a journey and was treated by a roadside mechanic, my car hasn't been in good shape.
I noticed that if i start the car in the morning, the RPM drops till the car shuts off. It continues to do that until i press down on the gas a little to stabilize the RPM.
My mechanic has changed the fuel pump, also the spark plugs coil. He's also adjusted the 'slow' but once i load the car with AC, the car starts vibrating and the RPM keeps fluctuating like the car is going to shut off again (all while not pressing on the gas).
We also noticed the alternator wasn't in good conditions, changed that also.

To the gurus in the house (CC Gazzuzz, Ikenna, Siena et al) come to my aid oooo