I have a 2004 Trailblazer that I recently did an engine swap. She was running great and then I developed an issue. When you first start the car up, she runs fine. Then after about 2-3 minutes of running I experience a loss of power/acceleration and the motor sounds like it's struggling/overloaded. When you floor the car the engine sounds like it's overloaded and I get a max of around 3000 RPM's. While experiencing this the "service engine soon" light briefly flashed on and then right back off. Any ideas?