1991 Eagle Talon Engine performance

I recently bought a 91 eagle talon, it had been sitting for 3 years and I am experiencing some minor problems. when car is cold, its idle jumps from beteen 1000-1500rpm, during this time the car seems to have low power and boggy. After about 5 minutes when the temp imcreases it runs much better with quicker response, this car is stock turbocharged and I was wondering if this could affect it, also after warm the oil gauge drops to low but no warning bulbs come on. Any ideas would be a great help.