Peoples opinions on this will differ, but I would say that if you're idling okay, within the 600-1000 rpm range, you're okay. You're not throwing codes are you?
When my TPS failed last summer it was rather obvious that it had gone kaput. I was idling at 1300 rpm, but that wasn't a huge deal (I still knew I had to replace it eventually) . The major problem was that while driving on the highway, if I let off the gas, my rpms would drop well below 500, then the engine would die. I would say that when that happens, you're TPS MUST be replaced. If it's not doing that, then it's probably okay.
2007 WK CRD | QDII | GDE ECO + DPF delete
1998 XJ | FbG | Moabs & Duratracs - Sold
1996 XJ - Sold