Toyota Repair: 2000 tacoma idle off and rough, union plants, assembly plants

Question
brief history:
bought a 2000 Tacoma here in Canada. the truck was from Oregon (US truck) with 95,000 miles. Anyways, I have had it since April '06, and the engine idle has gone up and down, and is very rough. you can feel the truck shaking...even the shifter vibrates. sometimes as your pulling away it seems like the truck wants to stall out and die.I should also add that the check engine light has been on and off ever since I bought it. I belive some of the engine codes were 300, and 301, as well as a code that meant engine idle. the broker I bought it through has already spent around 3000 bucks on it repairing most of the top end...bearings, rod, camshaft, oil pump. Spark plugs, and plug wires were just replaced today to try and remedy the problem, but I guarantee the engine light will come on again in a couple days, like every other time its been in the shop. The broker now wants me to start paying for the repairs, and I really cant afford to be shelling out dough on repairs. I have always loved Toyotas, and would like to keep my faith in them! I am guessing one of the problems is the Tacomas are now made by GM?

Answer
I need to know if it's a 4 cylinder or V-6 and no, tacomas are not built by GM, toyota has assembly plants in the US, most Tacomas are assembled in Kentucky at non-union plants.  To expedite my response please reply directly to my email address> tedrttr@yahoo.com/  I'm fairly sure I will have an answer for you, also it would help if you can tell me exactly was already done to the engine to try to correct the problem, be as specific as possible.