okay. just got some time to check the issue. I connected my obd tool and test the fuel pump and the fuel pump did run. then I searched again for the fuel pressure testing port and I finally found it. it's pretty obvious though. it's on the fuel rail. I originally thought it would be somewhere before entering into fuel rail. you need to take the top plastic engine cover to see it. it's on the passenger side on the front. so, I hooked up the fuel pressure gauge and use the obd tool to activate fuel pump. guess what... it read only 5-10 psi on the gauge. so, apparently, it's fuel delivery issue now.

it was already late. so, I didn't do any further testing on the fuel pump. first thing I did after back from garage was to order fuel filter online. since the car is already 88K miles. will need to replace fuel filter soon anyways..

plan for tomorrow is to test the fuel pump. since it's still running. I'll try to measure the amp consumption to find out if it's working properly. worst case is... another $300-$400 for the pump.