Your front end could be shimmed too tight, or it could be binding. Take the front hubs off, and use a 1/8" drill bit to ream out the hole the kingpin goes through. Do this by hand, until the block moves smoothly on the kingpin.
After that, reinstall everything the way it was. Then set the car on a table, and push on a front body post. If the opposite rear tire comes up, you have too many shims on the kingpin. Remove one, and do it again. DO that until the rear tire doesnt come off the ground when you push the body post. Then, lift the same body post. If the chassis lifts before the front tire, add a small shim to the kingpin. You can use motor shims. Keep doing that until you have the chassis lifting at the same time as the tire, and the rear tire not lifting when the suspension is compressed.
Repeat for the other side. What that does is allow the front suspension to work, your problem is likely that when you accellerate, one of your front tires lift because of binding or tight shimming.