95 F150 4X4 issues

1) I have a 1995 F150 4X4 with approxamitly 125000 miles. It shakes like heck when it is just about to downshift. More like a quick shutter. It was minor for a while but is getting worse as time goes by. Any ideas?

2) The truck use to have some ^&(*'s now it is slow to react to the gas. seemed to happen after I had it tuned up. (New plugs and wires and cap etc.) Any ideas?

Thanks in advance!