As I had posted before, I have a 92 formula with the L98.

It was missing when on the gas now that has given way to a complete shake of the car when running. The whole car engine ect is bouncing back and forthlike its firing on like 6 cyl. It almost feels like its starving for air when I drive it though it does it when the tube is off the throttle body too...

Could there be an exhaust restriction CATS how can I tell if they are bad or if they are causing it?

It sounds like its firing on all * but with the rough I cant tell 100% it also had alot of "gunk" buildup on #8 plug I also replaced...

last thing I had done to it was an injector service and for 3 days it was fine then all the sudden it started this its a pretty violent shake.

Please help cus its driving me mad and Im about to send this thing down the road and get something new...

-Danny

 

Get rental tool a noid light from the zone or o'reillys and check both side of the rails to see if they are both working correctly.
On my car just the passenger side was working and it was running real rough until I finally figured it out.

 

You saying the injectors were serviced, and in turn ran better for a few days leads me to believe a fuel issue is at the root.

Ever change the filter?...
Couldn't hurt to check fuel pressure too.
At the end of it all, if it still has the stock Multec injectors, I'd consider the possibility of them being bad. Use a multimeter and test each injector cold, then hot, then post the results here.