unknown issue

[southernmantis]

i got a 1990 ka24e 240sx.the problem is that some times the car will fire right up and then sometimes i will turn it on and it will just kick over other times it wont even do that. i replaced the starter and still nothing,even push starting it dosent work sometimes. i do know that there is a vaccum leak on the intake and im fixing that and also the car will idle really high at 2000rpms even after the engine warms up,and even so it shouldnt idle that high to begin with.i replaced that mass air flow sensor but not the clip and still nothing.the car is completely stock and it dosent have a hood so i know it has gotten a little rained on.if you guys know whats going on i would appreciate some advice.even just pointing me in the right direction of some former posts.i did find alot on high idle and all and took a look over those but nothing with the start problem.