Hello Blazer forum. I am having a a problem with my 1999 s10 blazer. The issue is that from 1st gear to 2nd (and sometimes 2nd to 3rd) my truck will shutter for a bit as if it's stuck between gears. The shutters are really violent and make me not want to drive it. It started doing it last winter and then went away in the summer. Now it's back. I'll list off every little problem I have to give an idea of the trucks condition:

In park if I rev of 3000 rmps the speedo will say I'm doing 20.

When the truck first warms up it over heats to about 220-230 and then never does it after.

The truck idles low.

Those are all the problems. I changed the 1-2 shift solenoid and that fixed the problem for about 1 day. I replaced the fuel pressure regulator and that fixed it for a little longer but the problem came back. any help on the matter would be greatly appreciated.