LIVES4CRAWLIN91

Hey guys, im a new member but pretty familar with the sight. I have a 1991 Toyota P/U, 3.0 5spd. well heres my problem. my motor has suffered a power loss, and i cant figure out why. if i am running the truck before its at operating temp, it has its "power" back, but as soon as it reaches operating temp, it dies off. and i have to really rev out the gears to get up 2 and speed out of 1st, now this is how it is a majority of them time, oh and my gas mileage has dropped to about 10mpg if im lucky, occasionally the motor runs excellent, now i was wondering if it could be my timing even though i just replaced timing belt, or could it be the fact i have my cat cut out and im getting to much air flow past my o2 sensor and its causing it to bug out. could it be the air sensor itself. im lost and havent been able to come up with anythin, ill gladly look into any suggestions, and its just to keep it going till spring when im going to sas and 4.3 it and a number of other things, oh btw the mileage on it is 261000.

TNRabbit

Sounds like a vacuum leak. When the engine is running rich (cold), it tends to overcome the excess air coming into the intake, causing it to appear to run properly. As soon as the ECU reads a warmed up engine, it reverts back to lean operation, which means you lose your power again. I had the same symptons & had a HUGE hole in one of the VSV hoses. Gas mileage had gone to hell & I had a miss as well.

THIS WORKS LIKE A CHARM: Use an UNLIT MAPP gas or propane torch & run it around the hoses with the engine running. If (when) it idles up, you have a vacuum leak there. Good luck; there are MILES of vacuum hose on this engine!

spainobain1234

My 1994 4runner has been acting up and not one person can answer my problem. If you have an answer please reply to me ASAP!
<br>Power loss, rattle from behind engine, revvs extremely slowly when cold, when going up hill, it decelerates and BOGGS down from 35 to 10 mph and then revvs up to 3500 rpm and bucks into 2nd gear trying to speed up, but it slows down. Also the vacuum hose from the fuel canister that plugs into a module behind the engine is unplugged; the man I bought this 4runner from tore the tube off this piece behind the engine and plugged the module with gum. Then I found the other tube that connects to that module is unplugged and behind the engine is still rattling. The Module is the tvv where the hoses are disconnected.
<br>
It just got a full tune up plugs wires cap rotor fuel filter. It feels like it is starving for fuel. But I have used fuel injector cleaner, sea foam, etc, and nothing helped. Now I think it is a sensor. When I fully revv the engine then let go, it slowly revs to about 1500 rpm. I have to hold the throttle and it slowly revs to around 5000 rpm. when I am driving, it has way less power than my dads three identical 4runners. 1994 and 1995 stock models. I go up a hill and it will not remain a constant 30 miles per hour, instead it drops all the way to 10 miles an hour as if there was absolutely no torque. When I drive I have to push the pedal to the floor, but it will not rev above 3500 rpm. My tranny shifts great so it isn't that I can guarantee it. I removed the EGR using deep creep, and sprayed inside each tube. Anyway, I drive on the freeway, it goes 60 then can go 70mph, but suddenly BOGGS down to 50 and I press the pedal to the floor and it remains at 3500 rpms but will not speed up. I have to drive at 50 until the power comes back and the fuel flows through a little better and then get up to speed again. ITS severe loss of power and It happens every time i am on the freeway. Plus The vacuum lines behind the engine are unplugged. From the fuel canister to the back of the motor and another line that plugs into the same module behind the engine. But the Rattling from back there begins as soon as I start it up and is unbelievably loud. The sound vanishes after 5 minutes, and then whenever It deaccelerates the rattling takes place. When I use low RPM's it rattles. Please Help!