power comes and goes

[mrbrink]

Hello all,
Within the past month or so, I've noticed that my truck's power level seems to fluctuate from day to day. Some days, it's really snappy and runs great, and other days (most of the time) its a total slug. Like, having to mash it nearly to the floor to get up to speed. I noticed more valve noise when its running strong, so I'm thinking the timing is changing. Is there anything I should be looking for?
The lift pump is maybe a month old, along with the fuel/water seperator on the firewall. The other filter was new when I bought the truck but thats not saying anything.
The cold start timing advance is working, I can hear it click off when the engine is warming up.

 

[SparkandFire]

How many miles on the IP ?

I had close to 200k on the pump in my brown truck, the cam roller for the advance (or retard) lever on the side of the pump was worn out and the pivot pin for the lever was worn too, very sporadic timing, same thing... Some days it was a champ, most days it didn't want to move.

Once a certain wear point is reached, the pump internals start to do unpredictable things too, if the pump has over 100k it could be worn out.

 

[mrbrink]

Well its got a rebuilt 7.3 ip, and I've put probably 1500 miles on it or so. It hasn't shown any of the signs my last pump did before it went, but I'll check that cam deal you mentioned. I seem to remember it didn't seem right when I put it on the truck...like it didn't do anything when I played with it when the engine was running...I don't remember exactly. I just put it on and the truck ran better than it ever has so I didn't worry about it