Intermittent Brake & Idle problem on Saturn SL2
 

My mother-in-law has a 2001 Saturn SL2 automatic that thus far has been completely unmolested, it looks like a new car under the hood.

Recently she has been complaining about how the brakes feel, like sometimes they are lacking braking power or something (she had a hard time describing it). Yesterday she pressed the brake when pulling up to a stop light and supposedly the pedal went to the floor though it still had some braking power, but when I sat in the car later the pedal felt fine to me. I traced each line and saw no hints of a fluid leak and the reservoir hasn't gone down, so I'm guessing it's probably the master cylinder. I haven't yet replicated this while driving though. Thoughts?

Also, since we got the car about a year ago, it has had an intermittent "issue" where putting it in park or neutral after driving it results in the RPMs jumping up to about 2500 and staying there (not surging). When first started the idle will eventually settle down as the car warms up, but after a drive it may or may not idle high when put in park. Putting it back in drive and taking it around the block and then parking it again will often cause the idle to drop down to where it's supposed to be. A while back I took some carb cleaner and sprayed around all of the vacuum lines I could find and found nothing.

More recently a CEL has come on and it idles around 3300 in neutral. I plan to take it to get the codes read tomorrow, but any leads would be welcome. It's been getting progressively worse but only recently has the CEL lit.

mine has done that some too, i think its in the master cylinder. the fluid in mine was very dark and flushing it has reduced the occurrence of this for me. i haven't changed my master cylinder yet though because i cant open a single bleeder, so i haven't had a huge sudden change. (flushed by sucking out and refilling master cyl, and extending and compressing pistons/cyls... hoping to do major brake rebuild this year, including all flexible lines which might be a potential cause of this too, although i doubt it) im guessing you have rear discs, but if you have drums, adjust them. they don't seem to automatically adjust for many ppl

The IAC on these cars are horrible. Mine has been nothing but problems since i started hypermiling the car. I have been running my car with the IAC unplugged for a year now. No longer does the car rev out like crazy just because the computer does not like my hypermiling.

Sure, i have to manually apply throttle when cold starting it, but I'm used to it.

The two codes that showed up were engine coolant temperature sensor and "secondary air injection system". I replaced the ECTS earlier today and the driveability improved a lot. Strangely, replacing the ETCS made the CEL go off but it still revs high in neutral so I'm thinking I'll still pull the IACV off and clean it, or even replace it and see if that helps.

The ECTS is the heart and soul of the Saturn and will cause all sorts of issues. You bought the good one that has a brass tip, right? If it is plastic-tipped, take it back and get the brass one. Also, did you notice any corrosion on the connector? If so, replace that as well.

If the high idle reappears, try turning the car off and then immediately restart it. If the idle returns to normal, then your TPS is bad or dirty. Remove the throttle body and clean it, the IAC and TPS. If you have to replace the TPS, get the Delphi/Delco part, do not use aftermarket!