if the car does not have directional tires move that wheel to the left front see if shaking moves with it. which would indicate a bent wheel. whoever balanced the tires would have noticed that. check for anything loose from ball joint install. static wheel balance is only good till about 60...
confirm spark first, like jakk220 said noid light set. see if autozone or advance will rent it to you for free, this will verify ecu and injector circuit proper operation. problem solved.
Run car to operating temperature and thermostat opens. Remove heater core outlet hose and check the flow. If it seems ok I'd suspect the blend door isn't making it to full heat position.
Did you check the front end for loose or worn components ? Balljoints, strut mounts etc. Bounce the front end up and down or have a friend do it while you listen for noise. Also you could drive and have someone walk right next to the car while you stop to get an idea where the noise is.
What were the results of the wiseman's test he linked you to above? Being that you have swapped two "known" good alternators and have relatively the same results it sounds like the problem is on you're end. I wouldn't trust auto zone very much either but I'd do a 2 minute test over 3 hours of...
Verify easy things first, fuses, relays etc. If those appear ok check if you are getting power to the fan. You don't want your fans running continuously for multiple reasons. Temp gauge could also be a problem not exactly sure need more details about the issue.
You have an oem clutch disc in the car with a built engine? Sounds like the clutch disc is toast and maybe it came apart or is coming apart. Can't remember but if there is a hole in the trans bell housing take the cover off and have a look for clutch material.
Sounds like the battery is weak or there is bad connection in the starting circut. I'd do a voltage drop test across the starting circut. Battery voltage may be good but how many amps is it putting out?
I'd start by pressure testing the coolant system if you haven't already. Let it sit for at least an hour. Was the 6 bolt head and block machined prior to the head gasket install and we're they both checked for being flat? You can take a spark plug out put that piston at bdc and blow...
By leak down you mean pressure tested? If so how long did you let the system sit pressurized? Sounds like a head gasket. What's you're fan set up I looked at your profile but no details in that respect. During a cold start is the exhaust white? Do you have access to shop air with a blow...
Go grab a Haynes manual and look over the wiring diagrams. Since you said you tried a known to be good cluster that dosent apear to be your problem. You said the sunroof stopped working as well that's a red flag something is wrong with power distribution on that circuit Find where that is fed...
Being that the car starts and runs the ecu doesn't appear to be the problem. Maybe the etacs ecu which is the body control module more or less is toast. Do the wipers work? Door locks work? A wiring diagram would help pin point the issue. Check for power and ground to the etacs.
Try power braking it and have someone standing over the engine bay listening. Also try bouncing the front end up and down with your weight to duplicate going over bumps.