E250 Knock Sensor location / fuel injector pressure

[Lar]

Hi, I'm new to the forum.

Problem Part 1:
I have a 1990 e250 6 cyl. 4.9L van. It is very dependable but recently would run hard after driving ab out 30 min. A mechanic (after a service) once told me my knock sensor was cracked. He was showing me location of the sensor (under the cowl) but I could not see clearly. I now want to investigate the sensor and I saw a picture of one at the following web address:

http://pa.partsandaccessories.com/pa...ue&showdc=true

However, I see nothing resembling it in the area where the mechanic was pointing. Can anybody pinpoint the location of the knock sensor and verify that it's the same part as pictured at the above address. Also if the sensor needs replacing would it cause the van to be difficult to start.

Problem Part 2:
In relation to the van being difficult to start I was checking out the fuel injectors. I noticed the #2 injector appeared to have a leak and I attempted to remove it. Upon dislodging it gas splashed out from the supply port on the rail, as if it was pressurized. Is this normal or would it signify that there is a blockage of some kind? Would it affect the remaining injectors along the rail?

Thanks for any support.

Lar