HELP!!! bad bucking and jerking

First, 02 Taco 4x4 3.4l: I was driving in second gear yesterday coming off a stop and went wot to pass someone. Next thing I know the check engine light is flashing at me, and the vehicle is violently bucking... Since yesterday, I have changed all 3 coils, plugs, wires, fuel filter, pcv, and maf... No change and all are oe componets. The vehicle starts and idles fine. It only misfires under load( climbing a hill or in first gear), or wot. It will only misfire after 2300rpm. Please help this is my dd... I am lost.

 

oh ya and no stored or present codes...

 

Has the timing belt been changed? Don't know if it is that, I'm just throwing it out there.

 

don't think the timing belt would cause this. If it jumped time it would run bad at idle...maybe a fuel delivery issue or spark issue.

 

Just thought of that after I hit enter lol. I was thinking of valve float at high RPM, but that happens primarily with pushrod engines that I'm more familiar with.

 

HMMM !

 

The timing belt was replaced 2000 miles ago. The truck only has 91k. Just removed the timing cover and it hasn't jumped time... It feels like it hits a wall when it misses... Just removed both cam and crank sensors, no cracks in them...

 

I would say valve float, but this is happening around 2500rpm and up...

 

Lights flashing indicating catalyst poss damage usually indicating lean mixture if you have access to a fuel gage attach and monitor under load see what psi is doing. That's a start also if u have access to a cheapo scan tool see what fuel trim and oxygen sensor readings r

 

I was pondering fuel pressure too.

 

Update, p1135 o2 code just popped up... Going to Advance to pick up a denso sensor. Thanks to any and all who have helped so far. What is fuel pressure supposed to be? I did not see any test ports on the fuel rail?

 

Did u test the sensor output,ie resistance check could be bad if its original which sensor is that can't remember is that pre cat or post.fuel psi if I remember is around 40 either way should be constant what u would be looking for if it was an issue is drastic decrease when engine exhibits mis.no fuel Schrader u have to tee in to fuel line.who knows you might get lucky with o2 sensor if u need specific info I can get it at work tommorrow.

 

Short term is 0% lt is 10.2%... My upstream sensor 1 o2 is showing 0v at idle. When throttle is pressed it hits .72v. I'm gonna start there and hope this works...

 

At 2k rpm does the sensor cycle or stay constant o2s should cycle

 

cycles .2-.4v

 

Check that the sensor has its full range ie lean mixture out see out put
Richer check output

 

Well trying to remove the sensor the stud to the converter broke, cross threaded... Whomever owned this taco before me did a number. Found an exhaust leak near the sensor, and it's a Bosch 02... The factory converter looked to be running pretty hot, gonna change it.

 

Is the element in cat melted? They do run pretty hot,also what stud,mounting stud for 02?

 

ya stud for the dang o2... The cat was almost glowing red, and caked with red clay! I've been scraping clay off of this thing since I bought it. I don't know if the element is melted, but I dont see how else to replace the stud...

 

Is the stud flush or some sticking up