302 EFI in '88 F-150. After several unproductive attempts to diagnose and fix erratic idle and rough running, raw fuel was found contaminating crankcase oil and enough fuel built up in cylinders while trying to crank it to prevent engine from turning over. Turns over with plugs removed. What could have been the original problem and have I killed it?

 

Replace the injectors, or you can try and have them cleaned. Best bet would be to replace them all. Sounds like you have leaking injectors, when that happens, the injector doesnt close fully and fuel keeps coming out of them causing a rich mixture and will have an affect on idle. It can also cause the cyclinders to fill up with fuel. If the cylinders filll up with fuel while its running, it could cause the engine to hydrolock. When that happens a rod usually gets bent. Raw fuel in the cylinders can also wash out the cylinder walls so the rings get damaged from no lubrication, this will cause a low compression reading. Might wanna check that prior to replacing injectors.

 

When you removed the spark plugs , how many plugs were loaded with fuel, one, some--all?