i hate overheating problems change the cap its probably not building pressure sufficiently that can cause overheating during idle. i had this problem also b4. great way to see if u have a blown HG also is to check if ur gettin extremely high pressure in ur coolant system when u take the rad cap off after a drive some pressure is ok but too much where the cap blows off is a lil too much blowbye. best way to check ur HG tho also is to get a leakdown test to see where it also can be coming from. GL on that problem i hate coolant problems more than anything else!
