I got a 1990 foxbody. On start up it rpms come down to almost stall then fluctuate and eventually settlers out. When driving i press the clutch in and the car stalls BUT if I romp the throttle 2500 or above the car will idle high then slowly come down to base idle. I've replaced the air filter , maf , iac , tps , cleaned and secured the salt pepper connections , cleaned throttle body. I am dazed and confused please help