Millenia Engine 2.5L Questions

Hi Folks,
I have some questions about a 97 Mazda Millenia 2.5L that I am working on, but first a short history.
This car was given to me after the owner damaged the radiator and seized the engine up. I completely tore it down, had it bored out and rebuilt it. The engine had gotten so hot when it seized that some of the plastic components, like the knock sensor, had melted. I replaced everything that looked bad, like the knock sensor (not cheap).
The car is running now, codes are clear, gas mileage is not so great, around 16. But I have two remaining problems I was looking for help with before I turn it over to a professional.
1. When I start the car cold in the morning, there is a metallic tap that develops in the left rear (Pass. Side) of the engine. It last for a short while, minute or so then goes away. My first thought is the timing belt tensioner. I have used a stethoscope and it seems to come from that spot. Any ideas?
2. My other problem comes when the engine is warmed up, at idle it tends to miss, not continuous. Just a miss here and there, maybe every 15 seconds or so. I have checked all my sensors. My plugs, wires, and compression all look good. Dist. parts are not new but appear good. I have looked for vacuum leaks? What else could it be? Could it be exhaust back pressure? The car seems to have plenty of power.
Thanks for your help,
Jim

in regarrds to your millenia knocking ist easy hydraulic belt tensioner on al v6 626 millenia engines must be replaced every timing belt.most people dont but. when the tensioner looses its tention it knocks against
the tensioner pulley it took me 1 year to figure this out on my millenia
if you take the timig belt cover and start the engine you could see it vivrating u must have the pulley to start the car [


I have some questions about a 97 Mazda Millenia 2.5L that I am working on, but first a short history.
This car was given to me after the owner damaged the radiator and seized the engine up. I completely tore it down, had it bored out and rebuilt it. The engine had gotten so hot when it seized that some of the plastic components, like the knock sensor, had melted. I replaced everything that looked bad, like the knock sensor (not cheap).
The car is running now, codes are clear, gas mileage is not so great, around 16. But I have two remaining problems I was looking for help with before I turn it over to a professional.
1. When I start the car cold in the morning, there is a metallic tap that develops in the left rear (Pass. Side) of the engine. It last for a short while, minute or so then goes away. My first thought is the timing belt tensioner. I have used a stethoscope and it seems to come from that spot. Any ideas?
2. My other problem comes when the engine is warmed up, at idle it tends to miss, not continuous. Just a miss here and there, maybe every 15 seconds or so. I have checked all my sensors. My plugs, wires, and compression all look good. Dist. parts are not new but appear good. I have looked for vacuum leaks? What else could it be? Could it be exhaust back pressure? The car seems to have plenty of power.
Thanks for your help,
Jim[/QUOTE]