A/C compressor question.

87 Ramcharger, I converted my ac to 134a. Changed the expansion valve, filter drier and clutch. Pulled a vacuum and charged it with the conversion kit. At idle, the pressures are right, but as soon as you raise the rpms, pressure drops off. Doesn't really blow cold. At idle the suction line will sweat some at the txv. The compressor growls some and I think it is bad. Am I on track with that? I wanted to be certain before ordering another compressor.