You mentioned in a rather "tongue in cheek" way that you "think" your clutch might be slipping a little in first gear. If it is slipping a "little"in first gear it would have to be "all gone" in 4th and probably unusable in 3rd gear also. So look at it from the performance end of 4th gear. If you shift it into 4th at say 50 MPH and it takes off and performs normally, you do not have a clutch problem. If however, you hit 50 MPH and put it into 4th gear and all you get is high RPMs followed by a very bad smell, you need a clutch overhaul now!

"If it was easy everybody would do it"!

Junqueyardjim