car stalls at stops and when put into gear,

What is your question?

My 97 Windstar has an intermittant problem: at times it stalls when taking off from a stop, also when putting it in gear. Other times is runs great, no problems. The check engine light is on at times also. I took it to a mechanic, he said I had an intake leak and replaced all gaskets on the intake manifold. also gave it a tuneup, it still has the problem. At times now, it won't stay running at all. The next day it may run fine. ??????????????????