Weird no start after oil change.

[Thedude5804]

i have a 1994 k1500 5.7 standard transmission. Truck ahd been running fine and ran fine sunday morning. I drove it to buy the oil and filter (5w30 high mileage and pf454). Then after the oil change it wont start. It'll crank for days but wont fire. I wasn't getting spark so, long story short, i got a new cap and rotor and new plugs and am now getting good spark (i checked the firing order 3 times). Fuel is fine too. i just bought the oil pressure sending unit and am going to replace that tomorrow i guess. Can anybody think of what else it might be? Tanks in advance!