dis module

So my check engine light has been on and tach has been messed and well I need to get my car smogged next weekend so I went out and bought a DIS module cause I was pretty sure that was the culprit. So I unplugged it and bolted new 1 on and plugged in. Started car, tach was going crazy as was the car but i figured it just had to get used to the new module. So let it idle for a few mins then I took it around the block. Car was still huffing and puffing kinda but it got a lil better the more i drove. But then I had to make a uturn and it died. So after getting it back started I drove it back home.

It seems like I don't know maybe the idle is too low or something but when I let off the pedal the car doesnt handle it too well but I did drive it for another 5-10 mins around the block and it did do better, when im going 25+ it fine but sometimes when I slow down the tach drops to 0 for a second then back up. Im tempted to put old 1 back on but I need to get it smogged =( I'm going to call my mechanic in a bit but just wanted to know if ne1 had any ideas/advice before I had to shell out some bucks. Should I try just letting it idle longer?
Thanks

how long have you been driving the car since you swapped the part? my v8 did the similar things when i swapped the mass air meter.

just been driving it today, should I just keep driving it and hope itll adjust itself?