This is on a '90 Legacy. It starts fine when it's cold, but when it's hot you have to hold the throttle tight to the floor to get it to start. It seems to run fine once it starts though. Plus, the check engine light isn't on. I'm guessing maybe something with the MAF sensor? This is my daughter's car, and I'd like to get it straightened out so she isn't stranded somewhere. Thanks.

Could be many things but your symptoms are in line with a coolant temp sensor malfunction.

The sensor send to the ECU the info that the engine is cold when in fact it is hot. The ECU sends to much gas and floods the engine (too rich a mixture).

That's why you can start with the pedal to the floor : you give the engine more air and that leans the mixture.

A possibility to investigate.

The fact that there's no CEL is strange though. When that happened to me (same symptoms) the CEL had been on for quite a while.

I'd agree with the coolant temp sensor diag.

 

You can get one for 20 bucks at libertysubaru http://www.newsubaru.com

 

you can pull the codes & do an active diag mode. Instructions on my site.

 

For the money, I'd probably just replace the temp sensor.