The problem consists of going from 4200 rpms last month to 3950 rpms with a heavy or light load and I dropped 3 mph also.I heard the valves might need adjustment or it could be a cam lobe issue.Can anybody put any input on this?

How many hours on the engine??

If you're dropping that much speed and RPM with a load, that's perfectly normal, depending on the load.

I got 45 hours on it but I use to be at 24mph with my regular load but now the rpms dropped by 200 and I'm only getting 21.i have no dents and to get my original rpms I have to trim up far enough that the prop blows out.

Cover the basics.... compression, cylinder Leak-down, prop condition. Verify those are good before digging elsewhere. Most likely not the prop but put a tape measure to it anyway. Just check that box...

I got 125 on all cylinders and my prop measures 12.25.

Need to do leak-down. Throttle wide open while checking compression? Sometimes, you may still have all the diameter but lost blade width and cup. That'll kill prop performance just as quick and not be as visible.

Ok will do but if the width and cup cup are worn,wouldn't it raise the rpms.

Probably so, but speed will suffer as well.

How are your fuel filters? Water separator?

Leak-down % is the next piece of info we need.

Since we are on the subject, i had a pd 37efi in shop today . Customer says lost some power. 54 hours. 42% and 44% leaking through intake valves pretty good. It also has a bit of a rough idle. Actually sounds like a cam but im sure its a leannlope. At what % leakdown has anyone had an effected idle from map sensor jumping?

To be honest mine had a bit of a lope when it was up to temp from the time it was new. I never thought much of it until I put heads on it that didn't leak and it went away for the most part. So it appears I may have had the condition from the time it was new. I wish I would have done a zero hour leak down test on my engine and tracked it every 10hrs or so afterwards.

Well the fuel is clean and vented,it idles great and and when wot it doesnt sound like it knocking but the rpms dropped and it seems to be picking up rpms really slow.In my case testing it yesterday it would jump to 3800 rpms then slowly climb to 3950 at a pace of 10 rpms per every 2 seconds when it use to just jump straight to 4100-4200 rpms.

Everything was fine,fat chicks on the bow helped with rpms.