1835 runs rough at high rpm

[Kansas1835]

I've got an 1835 with dual weber 44s in a 4 seater buggy. On a recent trip to the dunes, it would run really bad at high rpm, I could not power through it. It reminded me of a rev limiter. It seems to only run that way in the sand. At home on the gravel road or in the yard it runs fine. I replaced electronic pointless ignition, but don't know if its fixed since it always runs fine at home. Not a big elevation change from kansas to oklahoma, so I wouldn't think its jetting or carburetion, but I'm open to trying any ideas you guys throw at me.

Thanks.

[veeweeman]

Did you check fuel pressure?

[Kansas1835]

No i didn't, but now that you mention it my fuel pump went out down there so I borrowed one from a buddy and replaced it when we got back as well.