97 Tahoe: vibration and loss of power

[mpmccluskey]

I have a 97 Tahoe, two wheel drive, 5.7l engine. while accelerating to highway speeds i get a strong vibration that gets worse when i push down on the gas. If i take it easy accelerating, I can usually get up to 65-70 and it eventually "shifts" and goes away. this also happens going up causeways (the rest of my area is pretty flat). at speeds below 50, never an issue. Also, the service engine soon light frequently blinks while this is happening...the code reader shows "random misfire" and something about the catalyst sensor.

I just replaced all the plugs, wires, rotor and cap and no change. I'm thinking about o2 sensors next.

Would a U joint problem typically have a code show up?
Could this be something with my transmission? the torque converter maybe?
how much is a typical torque converter job?

Thanks for the help.

 

[crmzendrgone]

misfires could cause vibration, um loss off power could be a plugged cat.

 

[TheBeast99]

i'm in the same boat as cluskey here. my cats were replaced tho cuz when i got the truck it was spitting out codes for that.
i'll get a random misfire code too if i let that vibration happen too long.
had Sears do a front end alignment on it, since my wheels were bowed in i think. that helped a little bit, but there was one part they couldn't adjust because they'd never done it on that type of truck before (wtf really? it aint a new truck lol).
i'm gonna go back and have them redo the alignment AND tackle that one last adjustment they bailed on doing.

but ya, it doesn't happen to me under 60mph, and i only get that strong wobble\vibration if i really use power getting on the highway up to speeds higher than 60, or if it's me needing real power to get up a hill at that speed too...
it's annoyed me since day one.
once i get this alignment and balancing junk out of the way, i'm gonna try looking at other things to try to solve this. not being able to use all 255 horses to get on the highway aint any fun ;-)

 

[99ukon]

Check your plug wires i just had the same thing happen to me, one plug wire was bad, if you have dual exhaust listen to both sides while accelerating if one is fluttering then check the opposite side on the motor

 

[bowtiefreak]

any codes?

 

[our97ho]

been there done that do your self a favor and change your cats and 02 sensors asap

 

[Dlong30]

another common problem for this is the injection with clogged poppets... permanent fix is the updated mpfi spider assembly, you can try to put a can of seafoam in your last 1/4 of a tank to try to clean em out... good luck!