2001 Toyato 4 runner - Car sputters when I step on gas. Battery just changed.?

[tenderroni2005]

Here is the full Scenario:
Friday - went to start my car in the a.m. turned key, just heard clicks. radio/light are fine. turned key again, car started fine. Put $15 of gas since tank was low.
Friday after work - went to start car, 1st time all day. It just clicked about 7 times. waited a few min., car tries to turn over but doesn't. tried again, car start. Friday midnight - tried to start car just did the click thing. My friend tried to give me a jump, just got the click sound, no turn over. took jumper cables off. Few minutes later, car acted like it wanted to start, one more try and it started.
Sat a.m. - went to the mechanic-he put it on his machine. he said the battery is weak and sent me to advanced auto so their machine can do a reading - their reading said battery is good. Mechanic knows battery is no good and he changed the battery. Drove off and car is struggling. Now as I'm stepping on the gas, it is hesitating and skipping, just not accelarating. HELP!