A few problems w/ 98 vert

I have a few problems with my 98 gt vert, I'm hoping I can get some answers. First off, the car will turn over almost 20 times before it starts. I hooked up a fuel pressure meter to it and turned the the key to ignition (but did not start the car) . First time it read 0 psi. I turned the ignition off and on a couple times and each time the fuel pressure would go up higher and higher. Starting at about 10 psi, then going to about 20 then 30. After it reaches about 35 it starts fine. But, if you leave the ignition on once it reaches 35 it will slowly go back down to 0. Also, somthing is fowling up my plugs. every time I give it gas below 2500rpms the car misses like crazy. I can fix the problem for a couple days by taking some sandpaper to my spark plugs, but it comes back after about 500 miles. I also went to the track yesterday, and right before I got there my check engine light came on. It made me think twice about running, but I had driven 2 hours to get there. the first couple runs I noticed my idle getting rough. At the end of the night, it sounded like I was running super hot cams. the car still runs nice after idle, and my e.t. times stayed the same the entire night. I have a feelling the car is running a little rich due to the slight backfiring when I downshift to slow down. Any thoughts? OH yeah, the car is stock besides flows w/ turndowns, and no air silencer