I have recently purchased this car from my grandmother. She had only put about 2,000 miles on it in the five years she owned it. I was told that it would sputter when driving it after the car heated up. I took the car to a Subaru garage, they replaced the transmission coolant sensor. I brought the car home and replaced my own plugs, wires and coil pack.  The car now will not stay running. It stalls when the RPMs drop to idle. I have since replaced the TPS and this did not help. So today I cleaned the throttle body and it is still stalling, the car also has a new battery and all connections are tight and clean....

Please someone help I am very frusterated!

Hm well one thing that happens sometimes is one or more of the little hoses connecting underneath the air intake tubing disconnects but isn't easily noticeable. That can make it unhappy. There's two hoses, one each going to the valve covers, and a larger hose that goes to the idle air control valve. Subaru's tend to like NGK plugs best and sometimes have issues with others especially such as the Bosch+4. The wires it can be a bit picky about too. If the the TPS was replaced it also has to be adjusted properly so it knows when the throttle is completely closed.

I have used NGK plugs and checked all of these hoses. I'll try adjusting the TPS today. It did not have any issues with stalling until I replaced the plugs and wires. Maybe I have a defective set of wires? Thanks for your help.

Didn't read that quite correctly, I've heard a lot of guys having troubles with the wires.

Edited December 31, 201510 yr by RLD

Hm well if it was working ok before and it started after replacing the plugs wires and coil if you still have the old parts a simple test might be to put back on the old coil and wires temporarily to see if that makes any difference. Right on plug wires some people have had trouble with non Subaru wires but I don't remember if it caused this kind of issue.