sounds like 3rd gear is shot in transmission.if first and second pulled fine than thats it 3rd gear gone. may feel a slow or a delay in reverse also but with high stall converters little bit hard to tell if delay is there.
naw reverse is fine as long as ur going normal speed it pulls real hard in 3rd its just when u going down the track its feels like its slipping so u think 3rd is gone?sounds like 3rd gear is shot in transmission.if first and second pulled fine than thats it 3rd gear gone. may feel a slow or a delay in reverse also but with high stall converters little bit hard to tell if delay is there.