A friend of mine at work is having trouble accelerating with his Impala until it gets up to about 20 mph, then it is fine. He has had it to 2 transmission shops and both shops say it's not the transmission. One shop put it on a diagnostic machine. His mechanic still thinks it's the transmission and changed out the oil, didn't fix it. My friend is very short on funds. There is no engine light. Car has 135K and hasn't been tuned up since new. I suggested starting with plug wires. With very limited funds how would you proceed? I guess first testing the wires would be my suggestion.