Just started to have some high idle problems come up. 77 308 GTB that runs very good but lately after it warms up it idles around 1500rpm . Its not the old carpet in the throttle thing nor the high idle cam stuck so I am looking for suggestions here. I did a major last Jan. (belts , valve adj,carb sync/tune) and it runns a little rich but pulls strong up to redline. Thoughts please.