L series lump

my other half has a rover 200 p reg early type with the L series lump same engine in the freelander 1 anybody know why it jerks everywhere when changing gear its really a lumpy engine and also the alternator belt screams its nuts of when cold not looked at it yet but told its auto tensioning so could need a new belt they did not know on mg rover.org??

The lower engine tie bar can go soft allowing the engine to move under load and return when the load is eased which could cause the jerking? Iirc the belt tensioner is locked off once the tension is a manual jobby so needs to be adjusted.