My 99 Suburban with 135,000 miles starts great if the outside temp remains consistent. For example, two days ago it's was -2 and it started right up. By the afternoon it was 20 degrees in the sun and it just would not start. It cranks over just fine. Also if I were to start it up on a cold day and drive it to the store, it's hard to start when I come back out after a bit. I can even start it, let it warm up, shut it off for ten minutes and it struggles to start. I usually turn it over twice, wait 30 seconds and repeat usually by the third try it starts. But the outside temp change? It may be days. I've heard distributor to computer. Any ideas.