1986 K5 oscillates at 35mph
 

Hello. I have an 86 K5 4x4 with a 305 I just put in, and I believe a 700R4 transmission. It does have overdrive. I removed almost all of the vacumn lines as well as the smog pump. I replaced the quadrajet with an Edlebrock 750, I know this is too much carb, but it's all I've got in the shop. I removed the vac advance, and the problem is still there.

Truck starts right up, has a good idle, doesn't get over 190 degrees, put her in drive, shifts smooth from first to second, and then, at 35mph, is begins to act as if a govenor is removing power, and reapplying power, so she will hesitate from 35-40. If I push the pedal to the floor, then she bogs down. If I stay ever so slight on the gas, I can milk her through third gear, and get up to 55 or 60. I haven't tried to go faster than that yet. Its a project for sure.

I have the vacuum switch on the firewall drivers side hooked up, and also the elec connector on the tranny is on. I have played with the cable adjustment on the throttle body, and no joy. The tranny kicks pretty hard into reverse or drive, but shifts smoothly.

What is the other vacuum switch for on the firewall passenger side?

I bought the engine off of craig's list, and the funny thing is the guy said he got it out of another vehicle that wouldn't shift into third gear....that scares me. The engine will rev up like a champ while she's sitting in park.

I hope somebody out there can help me solve this riddle, I'm running out of time and money, actually, we're already down to just time...the money's already gone.

Thanks--Nate

waaay too much gas, u will never get the truck to run properly with that carb, if u have no choice, replace the jets with smaller ones