Rough idle at start up then nothing?
so basically I have a 99 base Boxster. Lately, call it the last 6 months, I have had a weird problem that I cannot sort out. Car starts up after sitting all night and has a rough idle. Car will shake a bit. This happens for about 2 minutes. IF I leave before this 2-3 minutes is up, as soon as I go forward, car will backfire a bit. Maybe 3 or 4 times. After about 100 feet, it normalizes. After 5 minutes its totally gone and car works and runs great. I have done the following:
Removed and cleaned MAF. MAF is about 4 years old.
Changed air filter.
New cabin filter. Yeah nothing to do with it but I did anyway.
Other than that nothing. It usually happens on colder mornings, say below 65 degrees.
Plugs changed about 8K miles ago. Coil packs never have been changed. Car has 115K on the clock.
Does anyone have any idea what could be happening? When I initially changed the battery, it went away. Granted that was back in June when it was quite warm. So....Thoughts as to what may be ailing my girl?