82 Dodge Diplomat Engine Stated Shaking Real Bad

I Have An 82 Dodge Diplomat With A 318 V8 In It That Jumped Timing. So I Replaced The Gears & Chain. It Ran Fine For A Couple Of Days Then While Going Down The Road It All Of A Sudden Got A Bad Shake In The Motor. It Will Crank & Run But The Engine Shakes Really Bad. I Got New Plugs & Looked At All The Vacuum Lines And I Haven't A Clue What's Causing The Shaking. Can You Please Help Me It Is My Only Transportation Right. Ps. Before All This It Had Been Sitting For A Couple Of Years. Thanks In Advance, Dennis.