i need help please

first of all my car don't start and when we do get it started it idles at 2000 then jumps down to about 500 and then back up again then when i drive it it hits 4000 rpms and stops sounds like its hitting rev limiter please help anyone i would really appreciate it also how do you check ecu codes and if you do help me thanx so much cuz i havent had my rex for almost a year now just cuz i don't know whats wrong w/ it

1-
The idle problem is probally the TPS sensor. I heard it's kinda hard to replace, your best bet is to get a new throttle body with one already installed. I you buy a new TPS sensor and put it on, the angle could be slighty off and create the same problem, also you need a ohm meter to put it on properly. So I've heard. If not that it's a vaccum leak, check all your vac hoses, change the PCV, vac leaks can make your car do strange things.

2-
Engine codes
http://www.c-speedracing.com/faq/06.php
this should tell you what to do or help find that problem.

3-
As for the car not starting, just cranking, huh! Then it starts sometimes. It could be the vac, but I think it is the main relay. The honda main relay is a part that always screws up. Its under the dash/ on the corner of the driver side kick panel. The solder joints on the board inside the main relay always crack. Get a new one from the honda dealership, its worth it. about ($150 can) Easy to install, just plug the new one in. DON'T be like me and get 8 from the junkyard and find out 1 only works sometimes.

I hope that helps ya, This is all the stuff I've done, heard, or seen.

thank you sooooo much i hope your advice helps me it means a lot thanx again

Check the rotor in the distributor, sounds like it may be loose.