S10 engine dies then revs...?

I have been having problems with my Chevy S10

I has been stalling but restarts,

Now the problem, in the last few days has gotten worse with the engine is reving a bit high sometimes when starting. Plus it maintains the higher rev when driving with the engine reving so I would be going about 5mph from a dead start.

Its not reving super high but, its not right. And its always the same higher rev.

This happens after a few hours sitting too.

Then all of a sudden after maintaining this highr rev sometimes, it will goes to dying/stalling.

stalling can most times be prevented by gunning it.

I tried cruise control on the highway and it seems to run fine under those conditions.

I have been told this sounds like a idler motor or vacum leak on the intake anifold.

Does this sound right?

thanks

Kevin