splot=StreamPlot[{y,(1-x^2) y-x},{x,-4,4},{y,-3,3},StreamColorFunction->"Rainbow"];
Manipulate[Show[splot,ParametricPlot[Evaluate[First[{x[t],y[t]}/.NDSolve[{x'[t]==y[t],y'[t]==y[t] (1-x[t]^2)-x[t]+0.5 Cos[1.1 t],Thread[{x[0],y[0]}==point]},{x,y},{t,0,T}]]],{t,0,T},PlotStyle->Red]],{{T,20,"time"},0.001,100},{{point,{3,0}},Locator},SaveDefinitions->True]