I'm gonna go nuts
 

My car seems to have the same trouble as many of the maxima's owner in here. (if not more)

Here is the problem, my engine hickcups during warm up where the rev goes up to like 1k then drops back down to almost 200 then up again.

after replacing my waterpump and retightened my timing belt, things seems to be fine for like 3 days THEN it starts

during normal driving or highway driving, its really hard to get the car up to speed, like its refusing to speed up, but once it got to the 35 marks, the thing would run like normal.

During the speed up, the car felt like its really heavy, or something massive holding it back.

I tried to pull the ignition coils one by one to see if there is a dead cylinder, none to be found, during normal idle, the engine sounds fine, but when the thing is in Drive, I can hear this rumbling noise, and the car vibrates, almost like a shaking.

Please give me some ideas on where I should start.

maybe your auto trannys going down the drain

yeah, I think so too, the thing had been rebuilt by the previous owner already, as for me, I got 8 K miles on it, bahhhhhhhhh, more money involved I guess!!!!!!

Don't think its the tranny or torque converter (could try changing the tranny oil to see what happens). Could be the ecu water temp sender (not the gauge sender) is faulty & causing mixture to be too rich. Once coolant warm enough, sensor comes right (or gets by-passed) & everything sweet. Had this with my old Pulsar/NX turbo - which wouldn't start parked uphill as a result!

so how would you fix the problem? locate the sensor and replace it? if so, where is the location of the sensor and how much would it cost ?

also, what are the signs to look for if the timing belt was incorrectly mounted (not timed right) beside the piston hitting the valves. One more thing, when I let my car runs warm after awhile, a waf a bit of exhaust to see if it was burning oil or the mixture was too rich, and I can detect this metallic smell, similar to that when you leave a frying pan on the stove for abit without cooking anything. Any ideas guys?

Not sure exactly where the sensor is, but look at tranny end of block (typical Nissan placement). It should have a two wire electrical harness as opposed to normal temp sender that just has a single wire. The sensor has a hex shaped body - most are designed so you can use spark plug socket to remove. Cost shouldn't be too expensive (here in NZ around NZ$50 or US$30). You'll know if this fixs problem as it'll instantly go away.

To check timing belt installed properly, use a timing light! If it's out by even one tooth, you'll notice lack of performance - but this will be across the whole rev range and not when car is still warming up. Valves don't hit pistons unless its really out - then engine is unlikely to start or run...

Thanks so much for the input, as soon as I get some cash, I will definitely bring it to a mechanic.