BREAK AND IDLE ISSUE

[RicoRx]

2 different issues here. I have a 2001 rx300 with 176k.  

Issue 1:  Recently I had my exhaust completely replaced.  After it was replaced, I noticed it was hesitating to accelerate. Doesn't do it all the time but noticeable. Did not happen prior to exhaust replacement.

Issue 2:  At the same time I have noticed it was hard to break. Breaks got really hard to stop. Sometimes at a full stop and car in gear after about 10 secs or so the break pedal wold push a little further down. As if some pressure was released. I checked fluid and thats good. No leak from calipers. Pumped breaks when car was off until it got hard.  Turned car on and got travel of the break pedal, so I assume my booster and MC are still functioning.  Any help would be appreciated.