3.8L Starting problem after sitting ???????

I have a 92 Olds silhouttee it started needing to be cranked alot before it started, then it died once while going 45 MPH so i replaced the fuel pressure regulator,( I dropped the ring that held it in though so i put in a couple from the hardware store that should not matter though should it?) now it has not died while driving but still does not fire for along time after sitting like it has no fuel until it cranks for 20-30 seconds, if its only been awhile since it was drove its starts fine though.
Can someone tell me what to check next??
Where is the fuel filter located?
Appreciated.

Usually the fuel filter is located under the rear near the gas tank itself, usually very close to being right between the rear wheels. While it is good that the (minivan?) hasn't stalled since you replaced the fuel regulator, I personally would have checked the filter first. If the fuel filter is clogged, it could cause this, as could a weak fuel pump. I would replace the filter first, if that doesn't do it, you may need to check your fuel pressure against spec. If this is the case AFTER you replace the filter, you should look at replacing the pump. The fuel pump is very likely inside the gas tank.