Sounds like it could be many problems. I would first do the fuel ecu mod. This allows the full pump to work 100% in any engine temperatures. I would also lean toward a bad coil(s), plugs, wires, IACV, MAF, 02 sensors, clogged cats, and faulty fuel ecu. The fuel ecu is in the driver side rear comaprtment, under the glass. I would first pull the codes, and poist up your findings, if any. I also have the PDF manual with over 4K pages, if needed. Have you personally checked the timing?