tranning or bad luck?

[bcm]

hello,
I have an 88 190e 2.3.I just replaced the tranning this weekend bought online from a salvage yard with a 90 day warrenty.The tranning is suppose to only have 95k.My problem is that it does'nt want to catch 3(40mph) gear when driving city limits,but on the highway it catchs at 60mph and driving is ok.I changed the filter of course,and even blow air in the modulator vaccum hose with my mouth(dont have a gage)to check for leaks.The air blow straight through,so pulled it lose and the hose was fine. So my first question; is the modulator suppose to take in air like that or dose the tranning need to returned. Open to all opinion.