Sputtering at 4k under Full Throttle

[Baddflash]

Been having a problem with my dd , '90 Lumina 3.1L/3-spd. It seems that when it is cool (under full running temp) it will sputter if I floor it past 4k in 1st gear, but if less than full throttle it won't do it. After 20-30 min it won't do it at all under any circumstances, this is what throws me off.

I'm really unsure of the cause for this so at the least I'm gonna install a new fuel filter cause I know it's due, and see if it helps. Car has recently gotten a tune-up and there haven't been any problems for months after that.

 

Any comments or suggestions welcome.

 

Thanks

[Baddflash]

It still acts the same but once it has be up to temp it won't do it again that day regardless of how long it sits or what eng. temp is. Only thing I can think of is the cat.

 

Anyone??

[GP1138]

Maybe a gasket leak? When the engine is cold, the metal retracts so as to allow vacuum to leak, but once the engine heats up, the metal expands and fills the gap? Just a thought.

[slick]

Have you checked anything yet? Start with the basics- spark and fuel.

[Baddflash]

I'm not some newb, I only ask questions when I actually need help; not cause I'm too lazy to walk out to the car and check for myself.

 

Well it's sort of hard to test anything with the vehicle not moving as it's limited at 4k, so everything is fine when I test it. I can rev it WOT to 6k after this warm up period no problems and it won't act up again that day no matter how long it sits. When it's cold if only I give it quater-to-half throttle I can surpass 4k with no problems so it's only at WOT when cold.

 

I continue to lean towards the cat, as it is the most likely culprit IMO.