Inconsistent starting problem. Help!

I have a 93/94 V6 24 Galant (Australian model). I had all the lifters replaced about a week ago (no more ticking!), but now she's playing up on me. Oh, and please bear with me, as I may not know what i'm talking about https://www.thegalantcenter.org/styl...lt/biggrin.gif.

After getting the lifters done, it was running perfectly, better than ever actually, but then 2 days later, it wouldn't start one morning. Battery seemed fine, all lights and everything worked, tried jumpstarting it, nothing. The engine was trying to start, but it just wouldn't kick over.
Anyway, I called my mechanic, and they came to my place to have a look. Tried to get it started for 1 - 2 hours, but to no avail. Suspected it might be a computer problem. Called a towtruck, they left. Here's the weird thing, about 10 minutes after they left, I tried to start it again and voila! it worked. It ran a bit rough, the "check engine" light was on, was blowing some smoke, and then it died on me. Got it started a few more times, each time it seemed to be running better. By the time the towtruck arrived, I was able to turn the car around and drive it up onto the truck with no problems!

So the next day my mechanic calls me and says that he can't find anything wrong my car. He said he's had it running basically the whole day, and has been taking it for quick drives around the block every hour or so to make sure it's all good (by the way, I 100% trust him, and he knows what he's talking about). So that afternoon I pick it up and I'm a happy (but somewhat confused) man.

It runs great for another 3 days, and then yesterday afternoon it wouldn't start again. Kept trying a few times and it eventually starts, check engine light comes on, blows smoke, then dies. Does this a few times, then runs fine again all evening (no check engine light either). This morning it wouldn't start again, and refused to start at all all day, so now i'm really worried. I just thought I'd see if any of you guys know what it could be before I bother my mechanic again. I'll probably get up tomorrow and it'll start just fine :roll:.