i got a problem, or i think i do

i just got my truck back from the engine rebuild. i think i have a problem but im not exactly sure. when in 3rd and 4th gear and around 3000 rpm and tryin to get spped kind of quickly but not hot rodding it, my truck doesnt seem to want to go. i dont kno what it is but ive come up with a couple of plausible answers,

1. just not boroken in good enuf yet
2. need some carb cleaner
or 3. (which i hope its not) the timing is off

now it only does it in 3rd and 4th gear, so what could be the problem here?

ALL OF YOUR ANSWERS ARE POSSIBLE, THE RINGS MIGHT NOT BE THOUROUGHLY SEATED YET, CARB CLEANER / FUEL FILTER DIRTY, OR TIMING OFF JUST A LITTLE / OR THE ADVANCE ON THE DIZZY ISN'T WORKING OR DISCONNECTED. I'D CHECK THE TIMING / VAC ADVANCE MAKE SURE THE PLUGS ARE GAPPED CORRECTLY, AND DOUSE THE CARB W/ SOME CLEANER, AND REPLACE THE FUEL FILTER, AND SEE IF THAT HELPS.

will do. i bought some carb cleaner 2day and it seems as if that did it, i could actually get my truck up to 4k rpms. never been there in my truck before..lol. but tha carb cleaner helped a bunch, ill prolly still get a new fuel filter

you really shouldn't beat it right after a rebuild . they say to baby it for 3 k after a rebuild then beat it . but im not a mechanic .

glad to hear the carb cleaner worked for ya, but like Bagged89Mazda said, i wouldn't dog it too much until it is broken in....although i have heard drive it like you would any how, but i wouldn't risk it tho...

My theory is; if it's a new vehicle under factory warenty....Run It! If you put it together and it feels tight.....go easy for awhile. If it's together right it shouldn't come apart. I doubt if they put 2,000 or 3,000 miles on those NASCAR motors before they turn them loose on the track!!

No, don't baby it!.
Go through the gears at 3-4k rpm accelerating and engine breaking that way the rings will seat properly.
Don't lug it though in high gear going 40 mph.
Just don't go 5k or 6k rpm.
Good luck.