Loss of power (perhaps a miss) in my 4.0L

[Mudderoy]

I'm getting a loss of power between 4250 rpm and 4500 rpm. Not as noticible in 1st as it passes through this rpm range quickly but in 2nd it's almost like hitting the passing gear when it hits 4,500 rpm.

Any ideas?

[4.3LXJ]

Is this in the 98 and is this recent?

[Mudderoy]

Is this in the 98 and is this recent?

In the 98 and not really recent. It has changed. When I had the bad cat it would get to 4000-ish rpm and just not make any power.

After changing the cat that went away, but this issue has remained. I don't think it's a plugged anything in the exhaust because I would expect it to hit a wall and not improve but after 4,500 rpm, she takes off, you can really feel it.

I'm wondering if it's the lifter springs, but again I would expect it to hit a wall and not change.

[4.3LXJ]

I really don't think it is anything like lifter springs. Personal gut off the wall opinion is the computer not liking your cam. But I have no proof of that