Golf IV / Jetta IV :: 2003 - ASR / Engine Light Came On

I have a 2003 Jetta GLS 1.8 5Speed. With issues.

The problem that I first had (and have always had since): While driving under 30mph but at random times, my ASR / ESP light and engine light will come on and my car will lurch and lose power (I can't go above 20mp at that point this is the limp mode that traction control puts you in I think). I have to pull over and restart my car. And then the ASR / ESP light is gone and the engine light stays on for a day or so. After restarting my car everything seems to function fine.

My car would also chug a bit if I didn't let it warm up in the morning it acted as though it would die. After sitting for a minute it would be fine.

My mechanic initially thought there might be an air flow issue. He found a hose that was cracked at the end but said I didn't really need to replace it. He taped it up and used a clamp to keep in place. I have no (ok little) doubt that it is air tight.

When the problem continued he thought it might be my MAF sensor. He had a used one and replaced mine with it. It seemed to work, I didn't have the problem again for some time. But it eventually came back.

Also, I started to find that when I came to a stop light my car would idle roughly. If I put the car in park it was perfectly fine. Later, I had an even more serious problem. My car needed to warm up for about 10 minutes before it would shift out first. After plenty of internet searches on sites like this, everything pointed to the N92 solenoid. I purchased all 9 solenoids online and had someone replace them. That seems to have fixed my shifting out of first problem.

I still had the ASR / ESP issue though. So I bought a new MAF and replaced that myself (very easy). I was positive that would be then end of my problems. But nope no change.

Recently I also find that if I slow down quickly, sometimes my car just strait up dies. After restarting all is well.

So if this isn't a MAF issue, what are the other likely culprits? Vacuum leak somewhere? How much would you expect to pay to have that diagnosed (I think they have machines that can test everything and locate points of failure)? Air-flow meter? Transmission control unit? I have heard that they are relatively cheap to replace Engine control unit?