Hello, new to site. I have a 99 suburban best truck I've ever had but I'm having starting trouble. I did a full tune up about 6 months ago when It was starting hard, problem seemed to go away. Now It overheated twice due to broken fittings on the heater hoses. Fixed that and it ran fine for a few days, now it won't start at all. fuel pressure holds at 55-60 psi, doing a compression test tomorrow. no water in the oil and doesn't appear to be any in the cylinders. any ideas would be great.