Yellow gas flame suggests incomplete combustion and the risk of Carbon Monoxide which is poisonous - good idea to get it resolved very soon.
Best not to use it but if you really must make sure widow open while cooking - may be wrong Gas Jets or not properly adjusted or blocked airways.
http://www.edfenergy.com/products-services/for-your-home/customer-services/carbon-monoxide-poisoning.shtml
Take care...
Peccavi, April 2009
