1995 Toyota Camry transmission

Transmission problem
1995 Toyota Camry 4 cyl Two Wheel Drive automatic transmissionl 3000 miles

I have a 1995 toyota camry , I did an engine tune up and after that I noticed that when I put it in drive and floor the gas pedal it jerks making some banging noise when it shifts into the first gear, it shifts normally into the other gears if come to a stop abruptly it makes that same noise, but if I accelerate slowly and also stop slowly I do not have this problem, the mechanic told me that the engine spacers are the problem could that be?