My 4.6 falls flat on its face at 3000 rpm's. If I put my foot to the floor at a light, I go though first and second ok but in third the rpms STOP at 3,000, go down to 2800 or so, then eventually builds back up. This is really annoying me now. I replaced plugs, wires, fuel filter, coils, cleaned my maf, you name it. Same thing every time. The only thing I haven't been able to do is measure fuel pressure when it does it. Anyone have this problem, or even better- a cure?

Thanks in advance.

 

I could be rong, but my truck at wide open trottle runs up to 30-35 in first, then 70-75 in second, so 3rd is really up there.
3,000 rpm in 3rd must be really cruzzin if you just left the light.

 

you say the truck stops at 3000 rpms, tehn goes back to 2800, then back up. after it goes down to 2800, does it rise up normally? im gonna throw out a couple of ideas for things you could check. first, have your fuel pressure checked. if its too low, then the engine isnt getting enough fuel, whether its a bad regulator or a bad fuel pump or maybe a pinched fuel line. if you have too much pressure, its prolly running richa nd could clog the cats. make sure the cats arent clogged, even if the fuel pressure is fine. this is mainly a case with older trrucks, but its worth a shot if youre running out of ideas. also, check your O2 sensors, if theyre bad they might be telling the computer that your engine is running rich, and therefore you computer will lean out your A/F mixture. thats all i can think of right now, maybe someone else will have better ideas. good luck and keep us posted!