Idle down time too long.

[DCON]

I have a novi 2000 on my car with headers and an x-pipe, thats it. I took off my egr spacer and polished it and when I put it back on I set my TPS to about .964 volts. My car started up fine and ran good, I took it for a test drive and warmed it up. I noticed when I come to a stop or change gears my idle takes a long time to come down. When I come to stop it stays at around 1500 rpms for about 20-30 seconds then comes down to about 900 where it normally idles. Sometimes it idles at 2000 then down. I cleaned both 10 pin plugs behind the intake and I tried to pull codes 4 times with nothing. I disconnected the battery and turned on the headlamp switch for about 15 mins and it stayed the same. Should I bump my TPS voltage to around 1 volt?