i have a 99 f150 that i swapped a 2000 pi 4.6 into. i can almost rule the motor out of the equation being as i just replaced gaskets and checked over everything last night and i cant even spin tires in mud while doing a brake stand, its pathetic. i can also hold the petal to the floor on the freeway and it wont go above 70. does anyone know of any tests i can perform to diagnose this problem? im down to 2 things that i think which are transmission or (this one i highly doubt) the timing gear and chain set i put on was junk. it was god awful tight but the motor has no problem taching up in neutral. feel free to ask any questions if you need any further info but any help would be very much appreciated

 

Did you replace your head gaskets ? and are your tourqe specs correct both sides. My friend replaced his head gasket on a chevy truck and the tourqe was off from one side to the other and his fuel pump was causing a power issue even though it was functioning just low fuel pressure. that solved his problem check your fuel filter as well. Thats all I can tell you just from what i seen with his truck course its a chevy.

 

Yeah I got the correct torque specs and order of the bolts from a shop service program on a computer. I just replaced the fuel filter too. Thanks for the response.

 

check that you have full fuel pressure at the rail, when the engine is being accelerated...sometimes the pump fail so it can get enough pressure at idle, but can't keep the pressure when more volume is needed.

 

i will go check fuel pressure in the next hour or so when i get home. i did a stall speed test on lunch at work with a friend. we looked up the stall speed and it said 2200 with 3.55 gears and i performed the test and it only went up to 1600 rpms and held for 5 seconds before the tires spun. checked the fluid and was about half a quart low and tried it again and it went to 1400 rpms and held and then spun. now how can i tell between a bad tranny cooler, bad tranny, or bad torque converter?