I recently acquired a 1993 Honda Del Sol with the 1.5l engine. It does like mini revs........ constantly idling up and down. I was wondering if it could be out of time. I was told that it was a timing problem but I didn't think that an interference engine could run while not timed properly without tearing something up....... any ideas??

 

The main reasons for this are a dirty IACV or the cooling system is not full.

Recently acquired car you should check the timing anyway.

 

This^

Also try cleaning the FITV and bleeding the cooling cooling system.

 

I had the same problem with a civic vtec ended up being the fast idol valve.