wrxmaster07

I recently purchased a 2000 ws6 and it has a fast 102mm nick Williams 102 tb ls2 heads 180 degree thermostat longtube headers and a mail order tune. the guy said when he had it tuned they pulled as much timing as they could because he wouldn't be driving the car a lot, he said that I need a 160 degree thermostat for the car to run and idle right. when I first start the car up, it wont stay running unless I keep my foot on the gas. but when I start driving it it is fine for awhile until I come to a stop then the idle bounces up and down and eventually stalls. do u thihk the thermostat will solve the problem or is it in the tune