Idle problems

When I start my '95 Toyota pick up it accelerates for a few seconds, then normal, then accelerates, then normal, etc. I was told by my mechanic that I need a new air motion intake sensor for $700 + labor. Any insight would be appreciated. Thank you! Ed

Sounds like a simple vacuum leak to me. Did this mechanic at least check for those? Did s/he tell you this based on getting error codes related to a check engine light? If so, post the actual error codes.