Weird starting issue

[entry1wound]

Hello,

I have a 1998 SL2 that I purchased as my first used car. There has been some issues, but none of them too detrimental or serious (hole in the muffler, alternator failure...that's about it). I take very good care of the car, never go past 3000 miles for an oil change, and new filters come round every 5-10k miles or so.

Regardless, I wake up one cold morning here in New York to warm up my car...everything goes fine. It starts, sits for about 3 seconds at 2,100 rpm for initial cold start, and everything is A-ok. Then, I go to wal mart after it's warmed up, grab some items I need quick, go back to the car, and start up. Normally, since the engine and all the associated internals are warm (coolant is also up to operating temperature) it would start within 2 seconds and sit idle at about 800-900 RPM. Instead, it starts, and as the rpms drop to normal idle, it almost dies...flooring at 300 rpm and then ramping back up to normal idle. There is absolutely no impact on the vehicle's performance and there are no strange noises or issues. I'm just worried that it may be an underlying issue that could turn into a problem really fast.

Thank you,
Dylan

*EDIT*
Fixed rpm numbers

[bluesl2]

Make sure you have a brass tipped ect sensor and clean connector to start with. It also sounds like the throttle body may need a good cleaning.