PUT a 302 C.I OR A 351 C.I.(WINDSOR) bOTH ARE A SHORT STROKE ENGINE, ALSO INSTALL A RV CAM THIS KIND OF CAM WILL LIVEN THE ENGINE AND MAKE I FAST AND YOU WONT HAVE TO CONSTANTLY TUNE IT UP AS YOU WOUL HAVE TO IF YOU HAD PUT IN A LARGER CAM.bIG BLOCKS ARE OK BUT YOU WILL HAVE TO BEEF UP THE FRONT...
most likely the filter was getting stopped up and when they flused it it removed the contamineds from it. it was nt getting the pressure it need to make it move