98 cherokee sport idle surge

I have a 98 Jeep Cherokee Sport Straight 6 with about 130,000 miles. Well Maintained. It always runs great, until last night. I went to start my car and it surged to 3,000rpms and stayed there for 10 seconds then crept back down to about 1,300 (still about the usual 900-1,000 range) where it stayed. It's like this in both park and nuetral. When the car is in gear it runs fine. It happens everytime I start my car since the first incident. Any help would be greatly appreciated. :frown:

A vacuum leak can cause this type of reaction as well as the TPS (throttle position sensor). Possibly other things as well... dunno.

-Vacuum leak(s):
"Get a can of carburettor cleaner, let 'er idle, and spray anything that's a vacuum junction - including the manifold to head mating surfaces. The idea here is to "fog" the connections - anywhere it gets sucked in is a vacuum leak.
Repair line leaks,"etc.. - 5-90

-TPS testing:
Scroll down to the 4th faq on the page...
http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

~Good Luck

From your description, I would not overlook the NSS.