You should look under the dash of your truck and the linkage for your wipers you start jerking on things. You should lube all the pivots first, then with the engine turned off disconnect the vacuum hose and put it into some automatic transmission fluid. Have a helper cycle the wipers back and forth, this will draw some of the fluid into the wiper motor. Then let it sit over night and then connect the vacuum hose and try the wipers. Jerking and tugging on things usually makes things worse.