intermintent stumble

[faithkustomsupholstery]

hey guys, for the past couple of months ive been having problems with my 2.9 ive replaced the cap and rotor and throttle position sensor , map sensor , checked the fuel pressure and volume. unplugged the idle air control and replaced every vacuum cap and line that i have. what the motor is doing youll be driving down the road and it will act like it is missing and loss of power, but if you hold it to the floor it comes back and goes down the road like nothing ever happened and this problem doesn't matter what rpm range your in or mph, it is alot worse after it rains, and if the motor is idleing it acts like it is about to stall, gets down to about 600 rpms for a few seconds and then comes back, these simptoms are random and have no pattern. If anyone has some ideas please feel free to tell. the motor came out of 87 ranger 2wd, used 88 computer and fuel injection harnesses if that might make a difference let me know. thanks chris

 

[necessaryevil]

remove your idle air control valve and clean it out real good with some carb cleaner and reinstall. i was having the same problem till i cleaned that valve out.