We stretch not ourselves overmuch (ου υπερεκτεινομεν εαυτους). Apparently Paul made this double compound verb to express his full meaning (only in Gregory Nazianzen afterwards). "We do not stretch ourselves out beyond our rights."

We came even as far as unto you (αχρ κα υμων εφθασαμεν). First aorist active indicative of φθανω, to come before, to precede, the original idea which is retained in Matthew 12:28 (Luke 11:20) and may be so here. If so, it means "We were the first to come to you" (which is true, Acts 18:1-18).