Ford Repair: misfire cyl.4, collapes, compression check

Question
QUESTION: I am getting trouble code P0304 on my 2001 Ford Escape with 131000 miles on it. I have replaced the spark plug cleared codes and same code returns, then i swaped out coil packs from cyl.4 to 5 cleared codes and same code returns,replaced upper and lower intake gaskets and swaped injector on cylinder 4 and 5 still same code,the only thing i can find in the vaccum is the largest line coming from the plenum near the fire wall that goes under the intake collapes when the car runs i am picking up a new hose tomorrow for that. but i don't believe it is throwing this code

ANSWER: do you feel a misfire when you are driving this? also do a compression test.
get back to me..
Chris P

---------- FOLLOW-UP ----------

QUESTION: You can feel and hear the misfire when idling when driving the moror runs fine. I did a compression check on cylinders 4,5,and 6. 4 was 100,5 was 125, and 6 was 150. I also put some oil in cylinder 4 and the compression came back the same no improvement.

Answer
heelo again. with compression at 100 and others being at 150. that is a great sign of a mechaincal failure inside the engine, 100 is very low to begine with and if the compression did not come up with oil then there is a good chance that there is a problem with a valve. generally compression should not varry more than 5 percent between all cyliners. I believe now that the engine will have to be diasembled and inspected. let me know what happens. good luck
Chris P