Rough Idle Questions

[parkaveguy]

Ok. I have a 1995 Buick Park Avenue, 3.8 NOT supercharged. The car has been running great until recently. About 3 weeks ago, my fuel pump went out. I pulled the tank out, replaced the pump and strainer, and reinstalled it. The car fired up right there and sounded great. About 20 minutes into driving, I was at an idle, and it began to idle extremely hard. Almost to the point of stalling. Putting the car in park helped for a second, but continued to idle poorly. I wasn't sure what would have caused this. About a week ago, I decided to check for vacuum leaks in the engine. I noticed the fuel line coming IN to the fuel rail was leaking fuel straight out of the small plastic connector and the more i wiggled it, the worse it got. I took the connector off and replaced all the O rings inside. This seemed to help, but only slightly. Since then, I cant find any more fuel leaks, and it still idles poorly. Its nowhere near as bad as it was when it was almost stalling, but I am getting terrible mileage so I know something is off. I have followed the fuel line all the way from the tank to the fuel rail and I know it isn't leaking, any ideas what it could be? When I was changing the fuel pump, I also noticed that the Intake Air Temp Sensor was NOT plugged in. So I plugged that back in. I unplugged it again and it seemed to help the idle ever so slightly, but still not quite there. Would a bad IAT sensor cause a rough idle? Has anyone else had any problems with this on this car/motor? I will take any help I can get at this point. Thanks!

UPDATE: I tested the IAT sensor and it was only receiving 3.5 volts from the reference and it was outputting only .03 volts at max. I replaced the sensor but alas, it still idles hard.

 

[MelsRegal]

have you done a fuel pressure test on the new pump?

 

[G-632020]

have you done a fuel pressure test on the new pump?

Not yet. I dont have a pressure gauge but that may be a good place to start.