94 3.8 liter- rough idle, poor exceleration until warm

[mustang418]

Hi, I have a 94 Ford mustang with 3.8 liter engine with a 5 speed. We have been having a runniability issue. When you start the car in the morning, it runs really rough to the point of dying. If you try and drive during this time it acts as tho there is just no power. When I push on the gas, sometimes it will just keep bogging and then bam it takes off! Once the car is warm it runs like a dream but for those first 10 to 15 mins it lacks power. It has an O2 sensor code. I replaced all four O2 sensors, mass air flow sensor, egr valve and the fuel pressure is between 35 and 40 lbs. I'm at a loss right now. Could it possibly be a temp sensor problem? Or any other ideas on what it could be?

[kjvw10]

Originally Posted by mustang418

Hi, I have a 94 Ford mustang with 3.8 liter engine with a 5 speed. We have been having a runniability issue. When you start the car in the morning, it runs really rough to the point of dying. If you try and drive during this time it acts as tho there is just no power. When I push on the gas, sometimes it will just keep bogging and then bam it takes off! Once the car is warm it runs like a dream but for those first 10 to 15 mins it lacks power. It has an O2 sensor code. I replaced all four O2 sensors, mass air flow sensor, egr valve and the fuel pressure is between 35 and 40 lbs. I'm at a loss right now. Could it possibly be a temp sensor problem? Or any other ideas on what it could be?

Check your exhaust pressure when it's cold and when it's warm.
Also check for water loss and possibly in your exhaust. You could have just enough water leaking past a head gasket that it is causing the problem. does the car overheat in the summer at all, I had this problem and it caused my Catalytics to plug up and got harder to diagnose as time went on.

[dorfboy]

You should check your IAC motor. It is your idle air control valve. An IAC motor is highly susceptible to carbon and coking build up. I would try to clean it out or possibly get a new one.