a few months ago my wife says her 1990 is running funny so i took it for a ride (50 miles round trip) it started out running a little slugish drove 25 miles no drastic problems noticed about 5 miles from home it acted like it was out of fuel then died, i got it started and crawled home - engine just would not rev no power obtained at most 5 MPH. I have drained the tank cleaned and changed the in tank fuel pump including the sock and gauge sending unit as well as the inline filter (by the way the manual only covers the inline filter replacement on coups it is much/much more work on a ragtop) still idles very/very rough and only crawls. desperately seaking advice !!!

Since you have Multec fuel injectors and they're known to fail...I'd start by checking each injectors resistance with a volt/ohm meter...each should measure around 16 ohms. The point is readings should be close to the same for each one. Remember to check when COLD....then run to operating temp. and check again when hot. I've seen bad injectors read low 2-3 ohms or high 40+ ohms. Either way the ECM on your Vette has a internal "driver" which pulses 4 injectors at the same time (most refer to this as batch fired)....one bad injector will cause the "driver" to shut down and kill 4 cylinders. I may be way off base, but that's where I'd start unless you know the injectors have been upgraded.   JMO

 Is there a code showing.........no sense just throwing parts at it....  

Howard...is it setting any codes, or turning the "Check Engine/Service Engine Soon"" light on? That would be the first place to go...check for codes.
Along with infector issues already noted, I would also suggest the ignition module could be taking a poop.
Check for codes first...that will usually point you in the right direction, so you'll have an idea of where to start.

check the codes as joel suggests but they are shown next to the speedometer digits. just another thought here...wonder if the egr valve is stuck open. by any chance have you taken a fuel pressure reading. with the key in the on position, it should be approx. 42 psi. when running it should be about 36 (in that area).

there are no check engine light lit and no codes ??????

You're descibing similar symptoms I had a few years back..... no power and no check engine light on my '89. Took it to our local GM dealer and they said it was the ECM so I paid for that but it wasn't the problem. They came back and said it was the fuel pump. Nursed the car home and replaced the fuel pump myself but that didn't help either. After much research I decided to replace all 8 injectors and bingo, car ran like new. The car had 120,000 miles on it at the time which made the decision a little easier. I believe the 89 and 90 both use the same injector and I found seceral technical articles explaining the original OEM injectors had an average life span of less than 75k miles.  

IT IDLES LIKE A BULL RIDE IN THE RODEO. haven't had time to get back on the problem since the holiday. my wifes 90 has 16000 miles.

in my last post the 90 wasn't ideling worth a ----. just moved the 78 and started the 90 to move it to a working area, the 90 started up and ideled fine pulled it out of the shop and wsnted to go for a drive a noticed the fuel gauge indicated the end of the driveway may be as far as i could get. will get gas tomarrow and check the fuel gauge reading. I just hate it when things act like the fixed themself.