Thanks Sunil. The fuel pump relay and overvoltage protection were replaced last year. I will check them tomorrow. I don't have dictributor cap and rotor on my car.
These are the other work done on my car previously.
1. Replaced cylinder head gasket (one month ago)
2. New wiring harness.
3. Valve job.
4. New mass air flow sensor.
5. New battery.
6. New fan belt.
Also, there is a code 4 stored in the diagnostic led read out.

Any help from the forum is appreciated.

Fred

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94 E320 Silver 210000 miles
94 740il Pewter Green 97000 miles- Retired
05 S430 4Matic
07 Lexus IS250