So I have a Kia Sedona LX 2002 and for some time now the van will turn over but not start. I smell a strong rotten gas smell.

If I pull the fuel pump relay from fusebox under
the hood then I can get van started and put the
relay back in and it idles high around 4-5 k and I
have to wait for it calm down to under 1 k before
I out it in heat otherwise it stalls and I have to
start all over again.  I thoufht it was the gas
brand because I changed where I got gas and it
was fine for 3 months but is doing it again so i
changed gas again and hasn't helped just
getting worse. I need some ideas to check as we
can't afford to take it to a mechanic. Only vehicle  
in a five person family with single income