2005 jetta tdi high idle

700-900 rpm

If you intend to keep your TDI self maintained/repaired, this is an impossible task without the factory repair manual which has detailed instructions for all repairs and whether or not factory tools are required. You can order one through your local dealer although they come up on eBay fairly often. There are few parameters on the fly by wire TDI that can be changed without the VAG scanner.

Sounds like the Oil Gauge sensor or level unit.

when you turn on the a/c the ecm increases engine fuel to compensate for extra load could possibly be a vacuum leak

There are a couple of things that come to mind. One is make sure the EGR Valve and intake manifold are not carboned up. I normally have to clean them every 60 to 80,000 miles. It will actually close up with Carbon and restrict air flow and make the EGR valve malfunction. 
Secondly, the diesel pump may just have a lot of wear and it is putting out too much fuel at idle. The only way this can be checked is by the dealer with a VW specific scan tool such as VAG-COM. With this tool, you can go in and look at the the pump timing and start injection quantity. 
I have the start injection quantity many times but you have to have the software and login to get the readings. Most dealers will not do this but would rather sell you a pump if it is off.
Remove the hose from the intake where it connects to the EGR valve and look at the inside with a flashlight. See how much carbon is accumulated. This may not solve this problem but will help with starting and performance issues if corrected.

Good luck and hope this helps. To adjust the Idle, it needs to be programed in to the ECM so i am thinking that it's a Carbon issues that is restricting the air flow which the ECM is compensating to keep the engine from stalling.

You could have a bad air flow sensor. Do you also have a lack of power??

Check your vacuum lines, make sure there is no leaks, and go from there, then all you electrical connection in the engine compartment.
I have a 1996 Jetta Trek Edition, the hoses, and wire harness, are so brittle, any movement can cause hoses and wire insulation to crack.

when cold it will idle a tad higher 850 - 900 is normal cold , and around 600 warm. if it is idleing high after warm up then check for excessive coke<carbon> build up in intake and throttle valve.

Here is the most common cause of surges and stalls and low idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

Have your timing checked. Retarded timing can cause the issues you have. A quick adjustment could fix it.