Hi there, Thank you for looking.
So yesterday I was going downhill on gravel road while looking for a camp spot along river side and noticed my ABS light is came on, my battery light went on and my rpms went down lower than idle rpms, so I pressed on gas (while rolling down the hill) and it went up and than went down again, I lost the moment and my engine died. I stopped and couldn't start anymore, trying to start, no cranks, dash lights are dimming out. Got jumpstarted, my engine started after cranking 5 times. Rpms jumping up and down, antenna was going up and down. Had it running on 1500-2000 rpms for about 15 min. stopped and couldn't start again. Next morning, no start, no power. Got jumpstarted again, after five cranks engine finally starts..rpms not jumping, after 5min started jumping again and about to kill the engine, I had my girlfriend holding gas pedal while I was packing, after I had to hold accelerator pedal while she was getting of the car and I was hopping in....engine died fifty meters after, I have lost my rpms.
Got jumpstarted 3rd time and finally rolled, driving with both foot...to keep rpms high enough on intersections and lights. drove for about 40 km started lost power totally, lost fuel supply ( I think), just made it off the hwy and had to call my dad to bring me another battery. got the battery and meter...had 11.4 on old battery and about 12,8v on new one. Made it home on new battery, turned engine a few times and started it again with no problems.
Today had my DVM on my battery terminals and had engine running.
13.9v - 3500rpms
13.8v - 3000rpms
13.8v - 2000rpms
13.7v - 1500rpms
13.4v -1000 rpms
12.4v - 600rpms idle....while on idle voltage is going down very slow
When starting voltage drops up to 11.4 ( I think) and than goes up to 12.7v or close to that. When engine is turned off 12.8v on batt.

Want to figure out what is wrong, before buying new Alternator. What brand do you suggest for alternator?

Thank you.
Roman.

My general rule is that a car can't run on a battery alone. If it won't stay running, I look to alternator. If it will stay running for a long time, but won't start, I look to battery.

You used to be able to hold something metallic on the rear of the alternator with the engine running and if it stuck to it (magnetically), the alternator was working. An old trick we used to try as a jumping-off point.

Your voltages look pretty good. 14v is ideal and your getting that when rpms rise and, but ive had a lot of volt meters hooked up to my past street/drag cars and they usually hold around 12-13v at idle which I never liked but car still charged and ran fine. So it looks like alt is working. You may have a bad or slipping belt and its just not slipping anymore either. Also bad ground or cables.

First I would inspect all cables and clean them up, look into the big 3 cable upgrade and make sure all grounds are tight and good.

Second have alt tested and go from there.

Sounds like an alternator to me, IMO. When mine was going out I starting loosing lights, radio started flickering, lost the tach, and the lost power to the engine. Jump started back after a while but it died again. Easy way to check is to start it up and when it's running, disconnect the positive battery terminal. If it immediately dies, it's about a 90% chance it's the alternator. This is from experience, as my stocker on my 97 went out 2 weeks ago. Not too bad to replace at all. Definitely have it checked first though, just in case. If it's bad, I recommend doing the CS-144 Cadillac upgrade. Pretty simple mod to do, and it almost doubles the amps from a stock one (80 amps to 140 amps) for about the same price. Found a coupon for advance online for $40 off a over $100 online order from Advance, picked it up in the store and they even kept my core so I got it for less than $75 total. (Minus the wiring harness) Just a little food for thought! Hope you get it fixed! If you have any questions just let me know!

I would do the big3 first and then alternator.

I have a Toyota alternator for sale BTW. It has less than 100k on it and is genuine Toyota from a pulled 98 4Runner engine.

$75+shipping and it's yours. Plus 30 day return guarantee based on PayPal and my invoice comments.

I was going to use it because I had the same problem but I did the Big3 and bought a new 860 CCA battery from Costco (high quality trust me!) And I've been good ever since.

This literally just happened to my 98 4Runner and It was the alternator.

Looks like it is your alternator.
At idle, 550 RPM, I get about 13.8 V and at around 1000 RPM, it jumps up to 14.4 V. Check the voltage with headlights and AC on.