Hi, Many of you know I've been battling this problem for over 9 months now. Took it to mechanics and still no answer, or false hope.

I have a 305 TBI with ported Swirl ports and headers.
When I try to do a burn out by holding the brake and pushing gas, the car would go up to 1000 RPMS and stay there mummbling. I would floor it let off gas, the RPMS would drop under 500 the car shakes a bit and dies. In normal driving this low end area seems to be really slow from the dig. however, as soon as I pass 5mph the car picks up and drives normally. Higher RPM drives and anything over 5mph is fine. I am just not sure why does it do this at that one specific area.

I did a totall tune up with new sensors all around. Changed the pluggs twice and put in a new Distributor. Installing Crane HI-6s helped, but the tach and the car would stutter from time to time, usually on warm up on cold days (noise). Mechanic checked for vacum leaks, and it was at 17hg on idle, and when powerbraking there was none!
My rear disc caliper has seized in closed position and that might be the problem but I don't see how since I have a drum proportioning valve, and hear no rubbing or sqealing.

I need some help. Or at least a troubleshooting suggestion that I haven't tried yet.

Thank you soo much.

 

Looked into the transmission at all? I assume its a 700r4 - you don't mention having 3 feet .

Converter could easily be faulty with a broken stator or other internal damage. Your 1000 RPM brake stall seems VERY low. I would expect more around 1500-2000+.

I also wonder if theres a problem with the low/reverse or even the forward assembly inside the tranny.

 

Possibly, but the tranny shifts firm and it does not slip. Its been maintained well. I've seen my left injector pour instead of spray right after this happened! I have re-built the tbi with new injectors new fuel pump wit new regulator and filter. The car would surge a bit at idle when shifted in gear but once I just tap the gas pedal the idle gets up to where it needs to be! It kinda sounds like a gas problem, or a sensor telling a wrong information to an injector.
However, its hard for me to find this out since I really don't have anyone to help me, while I watch what the injectors are doing!