98 ex 2.3 was giving to me my step dad could only get it to run by pinching off the return fuel line and it ran great for a few weeks then started acting up so I put new regulator and new fuel pump idle good but push gas it would not rev then back fire and die plug return line and ran great agian now even with return line plugged it wont run good at all ive put new regulator and pump new plugs wires both 02 sensors it will give a random misfire code is all please help

 

Stop throwing parts at the car. You need to do some diagnosis.

What code(s) are you getting?

Will the car start up and run at idle?

 

yes it will idle all day long as smooth as can be but when you toucn the gas it starts missing and ill have to get the codes tomorrow i can drive it down the road and one minute it seems to be running good and will rev and then its like it getting no fuel I checked fuel pressure and it was 75 psi which is too high then unplugged return line and it read 0 psi then plugged it back and it still reads 0 psi I changed fuel pumps it runs a little better but still reads 0 thought maybe the guage was bad went and got another one still reads 0 psi

 

Something is wrong w/ fuel pressure measurement arrangement. Car will not run w/ 0 fuel pressure.

good luck

 

Was there any work done to the car prior to it running poorly?

You may want to try a power balance test. Unplug an injector one at at time and see if the engine runs worse.

 

No the car is all stock and I have unplugged each injector and it makes it run worse the codes it gives is PO174 PO170 PO303 PO304 PO171 PO300

 

FYI, the codes start with the letter P and have four numbers, so your letter O is really zero. This may help you to search the codes.

I don't have a P0174 listed in the shop manual. Can you clear the codes, then restart the engine, then read them again?

Your first post was confusing, because I can't tell if you replaced just the wires, or the spark plugs and wires. Just want to make sure we aren't skipping something simple.

Your car has a distributor cap (I think). Have you taken off the cap to inspect the contacts and the rotor?

 

Yea plugs and wires and I have even tried another known good distrib didn't change

 

Texashonda was right about your fuel pressure reading. You need to get accurate readings to verify you have proper fuel pressure.

Clear then recheck codes like I mentioned before.

You may want to check the mechanical timing. Make sure the camshaft and crankshaft are in proper time. A timing light is another option.

Since you have an OBD2 car, can you get live data from your scanner? Fuel trims or any other readings?

 

I had them scan it at parts store but I can prob get one