Update: My mechanic buddy called me back finally and confirmed what you guys are advising: He thought fuel pump sensor most likely. Distributor cap and rotor also likely because the rotor's resistor goes bad. So I went ahead and ordered FPS(200k) and cap and rotor since they have 30k. He said O2 sensor could cause my symptoms by decreasing fuel when car warms-when car is cold it has rich mixture so car will run. but not too likely because it relatively new (20k). So I'll go ahead and change FPR,cap and rotor. If that doesn't work I'll trouble shoot crank sensor and O2 sensor. I'll update.