i have a stock 83 z28 with lg4 & 5-speed. i was getting trouble code 51 which means prom problem. I uplugged both harnesses from ecm, the car seems to run better. I do have the cc qaudrajet & cc hei. Is it okay to run without the ecm?

Hardly ok, but you could get away with driving the car like that to the nearest j/y to get a replacement ECM. You'll get terrible mileage, the chambers/plugs & exhaust'll soot up, & the car won't run as good as it should by far.

Thanks for the reply. I bought a 1226025 ecm from a junkyard yesterday, plugged it in and no trouble light. The ecm had 1983 camaro 5.0 wrote on it,I don't know if it's for a 5-speed or auto. I know there should be a difference. If it was for a auto would I show a trouble code ( I have a 5-speed). I'm going to change the plugs, wires, rotor button & cap..should I do anything else? It has a new oil change. Just bought it last week 84k miles

Ok. that sounds good so far.
You'll have to open the little lid on the ECM's and see what's written on the PROM. If they're the same then all is ok, otherwise we'll just have to search the net to see if their applications are mentioned anywhere.
If this nets no results then you could try to put your original PROM into the new ECM and see if it works then.
Sweet low mileage car you got there.
If the air filter's dirty it'll show, but I'm sure there's lots of lube points on the undercarriage. Get a grease pump, get under the car and give it some shots on all the nipples you can see. Check the brake pads and replace the fluid if it's somewhat dark.