My car starting doing this awhile ago, i changed the fuel pump, replaced the burnt plug wires, and plugs. I started it up and the car ran great. I drove it for about 10-15min than the car seems to missfire, and you can hear the exhaust crackle. I just went out to start the car and now it does this all the time. If there was something wrong with the o2 sensors would that affect when the car first starts untill it goes into closed loop?

 

I have done a compression test and i had 200-210psi on each cyl. I have good fuel pressure, spark from the coil. I pulled the fuel rails to see if the injectors were bleeding off which they are not. I was talking to my friends dad and he said i might have a stuck lifter causing a valve to stay open sometimes? What would be a good way to check, take the valve covers off and run the engine and watch for rockers not to move? Also the water pump, opti only have about 10k miles on them. I guess it might be the opti if not?

 

opti