Weird idle

[BIGJake111]

Drove the car this morning and it acted normal, then drove it again from about 9:30 to 10:00 and the idle got progressively odd. It was normal at the start of the trip but by the end idle would drop to 1.1k when the clutch was depressed then surge to 1.9 then drop back to 1.1.

I put the car in neutral and the idle continued to do this.

I first noticed it being odd at about the third stop sign of the trip and by the time I was later on in my driving I noticed that engine braking in third didn't have the same affect as usual.

No CEL and I have yet to drive the car again since the idle was odd, it's like the throttle is stuck barely open.

2000 boxster S, just had a dealer oil change a week ago today, driven only 4 days since then.

(Edit: just remembered, the stop I first noticed it on was a hard stop, this one stop sign has no warning and is around a blind curve, I'd say I had to use about 50% of the brakes power while normally I never use more then 10 to 15 when driving.)