4.0 hanging idle loss of power

[foxracing5491]

i have searched all the current threads on this same problem with no prevail. my truck is (yes) a frankenstein. it started out a 95 2.3l manual. i have swapped in a 99 4.0l engine from an auto. 96 transmission, wiring harness, computer and sensors to not have to deal with pats and so i wouldnt have a ignition timing problem.

problem started occurring right after i pulled my transmission last wed to change out my flywheel. had stripped some teeth on ring gear for starter from hydro locking. that night driving home i would push in the clutch while cruising and the engine would bump up to 3000rpms and drop to around 2500rpms and stay there. also while cruising i would leave the clutch out and let off the throttle and my truck would practically be driving itself staying at the same rpms. also when coming to red light, i push in the clutch and am completely stopped, the engine once again would stay at 2500 and will finally drop down to about 1000 after a whole 30-45 sec. the other thing is it seems like its taking off slower but but it will seem fine accelerating with a light foot, but if i try to romp on the gas it wont accelerate.

i have swapped the plugs previous to the transmission pull.

since this problem i have:
checked for vacuum leaks. nothing
checked tps. good working order
checked maf. good working order
checked throttle linkage. not sticking
i also plugged in a obd2 scanner with live data. the coolant temp sensor is working correctly. dont know how the scanner gets the percent reading for the tps but when i first start the engine it reads 18% while doing a test drive, at about half throttle it was reading about 50% but at the end of my quick 5 min test ride the percentage was sticking at 46% while pulling into my drive way on the throttle and also letting off the throttle and once it idled down still was sticking at 46%.

 

[dieseldane]

What method did you use to check your TPS?

 

[foxracing5491]

Multimeter, closed throttle was at .96 and wide open was just over 4 with consistant rise from closed to wot.
The other thing i forgot to mention is i tried cleaning out my iac, but i beleive the iac is just getting the wrong signal from the ecm.
What i am plainin on tryin next is to check my fuel pressure and to change my fuel filter

 

[foxracing5491]

i dont believe the fuel pressure is the problem but i might as well check it any way. along with changing the fuel filter.
The definite problem seems to be the computer thinking the throttles always at 46% but i dont want to purchase a $100 tps and throw it in and have the same problem.
but the other thing is even when the live data was saying 18% to begin with, the idle was still hanging.

 

[foxracing5491]

just started hearing a whistle as i shut my engine down. i am positive now its just an air leak. i still cant find it tho. im planning on just removing the whole intake and replacing the gasket and just check all the vacuum lines while its off. dont get how a whole can of carb clean didnt point that out.

 

[disciplerocks]

Vac leak or IAC. Although the IAC would cause lack of power, just more of a stumble.

 

[foxracing5491]

thank you guys for all the help and sorry for not letting u guys know the answer sooner, found what was causing the whistle, cracked line from the canister goin to right before the tb. but the probem in the end was the iac, swapped it out and walla