Left Front vibration

My 2000 Impala (3.4, 140K miles) has a steady vibration in the left front under acceleration. It does it whether its accelerating from a dead stop or getting on it while on the interstate. When I let off the gas it stops vibrating, when I get back on the gas it vibrates. Any ideas on where to start or is this one of those problems where I start with a hub replacement and go from there?

replace the axle,dont trie any thing else

sound like the exact problem im having w my 00 impala 95 k miles. the left vibrates when im going on an interstate. I feel the drivers door vibrate the most. let me know what you do to fix it. im gonna just correct my tire pressures.

im a mechanic for 20 years,
my friend have a 2002 ss impala,he live in ny and i live in nj,he callme for that
problem and i tell he what to do,bot he dint he toke to ia aligmet shop and he spend $800 and the problem was there then he call me back im fix the axle for $65