Here's what's going on.. this doesn't happen all the time just sometimes.. my thermostat is set at 67 and the room temperature is 67 so why does my furnace keep coming on but not completing a cycle ? It will come on and what I guess is the first stage the burners fill with gas and right before it would normally light it shuts off and doesn't light ( I did replace the ignitor) the blower comes on than turn off and immediately this process will repeat and this will keep repeating itself until I shut the furnace off at the thermostat or raise the temp setting.. can this be a bad thermostat? Because I don't see why it would even turn on if the room temp is what I have the thermostat set at..

It sounds like the flame sensor/ millivolt generator/thermal couple. Which ever you have try to clean it and see if it helps. Also this may help you if you have a mechanical t-stat. The heat anticipator is an electrical resistor device mounted in the center of many mechanical thermostats that fine tunes the point at which the thermostat turns off the furnace burners. It anticipates the flywheel effect of a space heating up and turns off the burners a short period before the space reaches the desired temperature.
The heat anticipator essentially consists of a simple thin wire mounted to a disc which is attached to the bimetallic coil. There is an adjustment arm which touches the wire and functions to vary the electrical resistance of the wire which in turn varies how hot the wire gets. This in turn warms the bimetallic coil causing it to shut down the gas burners early as determined by the heat anticipator.

http://homerepair.about.com/od/heatingcoolingrepair/ss/adj_anticipator.htm

If I have helped you I can use some tips out there people. Tough times.

I believe the proper way to adjust a heat anticipator is to first, after proper installation of the thermostat, put t-stat into heat and take the (W) Wire coming from the heat terminal on the terminal strip of the heater, coil it up 2 or 3 times and put your clamp on amp probe meter around coiled wire, measure current. Then divide measured current draw into however many coils you put through the meter and whatever that number is the adjustment you need to make on the heat anticipator. After doing like this for 12 years I have never had to re-adjust another one. Just my thought maybe you can share it.

I guess the first question is? Is the furnace keeping the desired temp in the house? Second question why did you replace the ignitor was the furnace not lighting? Your thermostat is made to maintain a constant temp at a set temp. If the furnace tries to light and fails it will try again. Dirty burners, low gas pressure will keep it from lighting.

Than what would make it come on lets say 3 times in a matter of 5 minutes never igniting?but if I up the temp 1 degree it will ignite and run?its seems as if the furnace doesn't know what to do.light or not light.

It is not your burners or your gas pressure. Check the things I said and you may be done with it.