[Dave99se]

I have 99 se 2.0 L. Ever since I got the car (3 years). It has always had a rough idle. I had 2/3 motor mounts changed, one of the transmission mounts included. After that it got a little better. I changed 2 of the breather hoses, the one that comes off of the valve cover and the one under the throttle body. I changed the pcv valve as well. I also changed the spark plugs, plug wires, and ignition coil.
So when the temp on the car warms up and I’m sitting at a light, the rpm’s start to go up and down between 500 and 1000 and eventually stays at like 900. So basically I don’t know if it’s running too lean or vice versa. Anyone have the same issue? Any advice or help is greatly appreciated

 

[zzyzzx]

How many miles are on this car?
Does it still have the original IAC?

 

[Dave99se]

How many miles are on this car?
Does it still have the original IAC?

About 73000 miles. and yes I have the original idle air control valve.

 

[pextor]

Did you get a Motorcraft PCV or a parts store special? I had idle issues with my old 99 sedan with a "bad" PCV valve.

 

[MenaceMan47]

Check for a rotted rubber hose that plugs into the bottom of the throttle body; mine was in pretty bad shape when I had to replace it. It caused a vacuum leak which created a loping idle and a CEL at times. $1 at AutoZone and it was fixed.

 

[marclar]

as stated, check for cracked and old vac hoses. also its very possible the intake gaskets are leaking.

 

[EscortGoddess]

I have 99 se 2.0 L. Ever since I got the car (3 years). It has always had a rough idle. I had 2/3 motor mounts changed, one of the transmission mounts included. After that it got a little better. I changed 2 of the breather hoses, the one that comes off of the valve cover and the one under the throttle body. I changed the pcv valve as well. I also changed the spark plugs, plug wires, and ignition coil.
So when the temp on the car warms up and I’m sitting at a light, the rpm’s start to go up and down between 500 and 1000 and eventually stays at like 900. So basically I don’t know if it’s running too lean or vice versa. Anyone have the same issue? Any advice or help is greatly appreciated

I would change that third mount first. I know it’s a tough one to get to and you may have to let the front of the stabilizer bar down and might have to Jack up the engine ever so slightly to get the mount out and the other one back in but mine ran like a champ afterwards.
if that doesn’t work there is an air temperature sensor (not the air temp control valve) I believe is mostly an electrical part