my pick up started with a bucking every now and thn now it is bucking Severly jerking

What is your question?

I noticed out on the road every now and then it would jerk once or twice. In the past 3 days a lil bit of a rough idle but driving around a mile or two it has started BUCKING very hard not like it will die but just a bad bucking and jerking can a loose plug wire cause this to happen. It dos not pop or anything. Plus it started doing it so bad immediately after putting gas in my tank I mean all i did was start it up went about two feet then it bucked all the way home 2 miles. after leaving home I went to my moms 2 miles it did not buck at all. Today I went to store a mile away bucked a coupl.e times. went to walmart and back to my moms about 3/4 of mile from my moms it started bucking really BAD What can be the cause of this

What makes this problem better or worse?

i dont know but when i give it the gas hard it seems to stop as bad or when i let entirely off the gas does not pop or anything

How long has your 1996 Ford Ranger had this problem?

it started just a mid jerk about 3 months ago but the mechanic said he cant find anything. yester 3/15/18 it started REALLY BAD after feeling up with gas.