My grand am gt is having idle issues. I have checked for vacuum leaks there are none. Put a new idle air control valve on. Cleaned the tb. And my car still idles at 1500 rpm in park and around a 1100 in drive. I also noticed when driving it around 50 mph it runs around 1500rpm but when I let off the gas it will stay there for a few seconds then finally drop. So I was wondering do u guys think I might be having my tps sensor going out? Also when I checked the vacuum line when I pulled the line that runs from my back valve cover to my air intake tube off the idle will drop to normal but spit and sputter. But once I put it back it jumps right back up to 1500 rpm. Any help will be very apprieted. Thanks