97 starting problem

My 97 Suburban just stopped running. It was running fine one night and when I went to start it a couple of days later it would not fire up.

Here are the symptoms.
Turns over fine until battery dies.
Fuel pump runs (I hear the whine when I turn the key)
Fuel filter has been replaced
Spark is present on the one cylinder that I tested.

One other tidbit. I recently got an oil change at Goodyear when I bought some new tires. Prior to the oil change my oil pressure gauge hled steady at around 40 -50 psi. Since the change the gauge reads 40psi when I am accelerating and but drops to 20 when I am idleing or cruising. It is around 40 psi when I am cranking.

I have not check the distributor yet but am assuming that it is ok since I have a spark.

Could my oil pressure sending unit be bad?

Thanks in advance for the help.
John

Did you get an engine code before it died? check the crank shaft sensor, just repl mine. same symptoms. fired right up. also cam shaft sensor at same tiem is reccommended, so i didnt do it. LOL.

good luck