low on power
 

I have a 94 F150 with 4.9 straight 6 and 5 speed. It has been running bad for awhile. losing power and wont climb hills without downshifting. Just all of a sudden happened one day. has good compression, replaced fuel filter and injectors. has good fuel pressure. tuned up. replaced egr valve, fixed vacuum leak. cat has been removed. has code 172 oxygen sensor lean. smells like gas when driving and only getting 10 mpg. after fixing egr code also got new code 225 knock sensor. Dont want to throw money and parts at it. any ideas what to check? couple of memory codes are 522 not in park, its a stick. 553 and 565 which has been there for years and ran great before.

Sounds like one or more cylinders are not firing. Have you tried checking the distributor?

What should I look for when checking distributor? I drove it again yesterday after it sat for awhile and it felt like maybe there could be a miss but wasn't sure.

You say it has good fuel pressure - did you check that with a gauge ? What was it at ?