magcomp

My 1993 Lexus SC300 recently has a problem with the engine stalled while driving. The milages are under 60K. I have a mechanic work on it and he found the fuel pump driver module voltage was intermittent. He replaced the control module and the car run for 3 months. My car now has a problem of starting the engine for some unknown reseason. Sometimes it starts instantly and other time it cranks but not running. I noticed when leaving the house at daytime it is fine but at night it will not start. The car has a new battery and I live in California so at night the weather it is not super cold. What's the cause of this problem? Please advise. Thank you!