Lots of things could cause this. If your sure its not fuel related there are many things in the fire area to cause a problem. Weak plugs or wires, coil, pickup plate in distributor, crank sensor and so on. A person with a good scan tool that knows how to read it could help you there. The problem with todays vehicles is there are so many things to cause a certain problem you have to have good diagnostic skills or play hit and miss with parts which at todays prices is costly. Hope you can find it.