Hey everyone! So I have a little bit of an issue. My car has been idling pretty rough lately (89 iroc-z 350tpi 5.7l) The car is pretty much all original (with some of the exceptions being the fuel pump that I replaced 6 months ago and the distributor cap along with a couple other things). What happens is when I turn my key the engine starts sometimes, Idles pretty rough for a few seconds, then dies right away. Sometimes it doesn't turn over and all I hear is the click from the starter solenoid. And sometimes it starts perfectly fine. When I start it up after a couple hours I usually get a white smoke on startup that lasts for 2-3 minutes, which I'm assuming is either moisture or the valve guide seals (but i only have 53k miles on my car). So I'm wondering, does anyone have any theories as to why my car is having a rough time idling (stays between 600 and 400 rpm, car likes to shake pretty violently at 400rpm so I give it a little gas) and when it's at I'd say 1000rpm+ or when you're driving you don't notice it at all. Also I haven't serviced my throttle body yet which I should probably do haha. Any help is appreciated, thank you for your time everyone!