Hi,
As per the subject line.
This started to happen to me on a regular basis.
So! -- Fri. morning after Thanksgiving - once I got the car actually started and running - I checked for vac. & other 'leaks' around the usual suspects -- egr, iac etc. etc. None found.
I then also removed/pulled out the two black/hard-plastic vac lines that are ON TOP of the manifold (on my V6). They felt 'secure' - not loose and whilst I had them 'loose' I decided to avail of the opportunity and poured in some Seafoam (into the UIM and also down into the vac. tubes). I made sure they were WELL seated when I replaced them. (NOTE! -- if you pull *either* of these vac lines -- with the engine running -- you will instantly kill the engine).
Then off to the fuse box -- I took out the relay and the fuse (#9 and #11) for the car's computer -- for the ubiquitous 30 seconds then re-inserted them.
Restarted car and gave it 10 mins of 'relearning' the idle - with the brake(s) on and the car in drive with/without a/c on - defrost off/on -- in neutral etc. etc.
etc.
Now, when I start it - she instantly jumps up to 1500rpm -- then slowly (after approx. 5 secs) goes down to 1,000rpm -- then the rpm 'rachets down' until it finally idles/settles at a constant (approx.) 750rpm.
:-)
G.
(And, yes, I regularly put HEET in during the winter and use Berryman's B12 &/or Seafoam / Techron etc. etc. -- so was 'pretty sure' it wasn't a case of 'lack of basic maintenance'). No CEL or pending codes (according to my Matco 9620 obdii scanner).
Car runs absolutely fine now.