I have a 95 GMC sonoma 4.3 vortec with 191k miles. Having problems w/ cold start. Troubleshooted down to fuel delivery, at least I think so. Here's my fuel pressure readings. Static: 58psi, but it drops like a rock. 48psi in 30 seconds, 42psi in a minute. Running: 54psi. Dead Head: 68psi. Changed fuel pump, but no major improvement in readings, and no improvement on cold start. Warm start is no issue at all. Recommendations?