Chrysler Repair: 2001 Intrepid RPM surge after work, vacuum line, work question

Question
QUESTION: I just replace the water outlet pipe on my mothers 2001 intrepid 2.7L

After reassembling I started the vehicle and it continues to rev up to about 3-4K and bounce as if hitting a rev limiter, i'm assuming a cold engine limiter. I've gone over all the vaccum lines I disconnected and all the plugs. Everything is plugged in and I replaced a cracked vacumm line coming from the PCV to the valve cover. After replacing the line, no change. I also reset the ECU, no change.

I'd appreciate any tips. thanks.

ANSWER: Hi Alex,
Try getting fault codes with the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to see the mileage change to read 4-digit number preceeded by a P. Let me know what they are and we'll go from there.
Roland

---------- FOLLOW-UP ----------

QUESTION: Thanks for helping me Roland. I just went outside and got the fault code: P 1684


-Alex

Answer
Hi Alex,
That code simply means the battery was disconnected recently, so is of no relevance. To rev as you describe requires that either the throttle body be ajar (so you might want to clean the throttle body throat, both sides of the butterfly plate, and idle air side passagewar, with solvent. The other possibility is that you have an intake manifold leak either around a sensor (or of course a vacuum line, which you have inspected) or around the margin of the intake manifold proper due to a gasket leak. Check around the edge by putting very short squirts of starter fluid on the seam while the engine is idling (racing) and see if you can cause a momentary change in the idle by doing so. But of course use very short spritzes so as not to start a fire. The feedback systems of the engine will make up for the tramp air leaking in by increasing the pulse width of the injectors so that is how you can get a revving situation such as you describe.
Good luck on finding the problem.
Roland